Fix: __asm_copy_to-from_user() having overrun copy #31
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This reverts commit 36e35cd.
…ess and pipeline stall" This reverts commit ca6eaaa.
…pipeline stall This patch will reduce cpu usage dramatically in kernel space especially for application which use sys-call with large buffer size, such as network applications. The main reason behind this is that every unaligned memory access will raise exceptions and switch between s-mode and m-mode causing large overhead. First copy in bytes until reaches the first word aligned boundary in destination memory address. This is the preparation before the bulk aligned word copy. The destination address is aligned now, but oftentimes the source address is not in an aligned boundary. To reduce the unaligned memory access, it reads the data from source in aligned boundaries, which will cause the data to have an offset, and then combines the data in the next iteration by fixing offset with shifting before writing to destination. The majority of the improving copy speed comes from this shift copy. In the lucky situation that the both source and destination address are on the aligned boundary, perform load and store with register size to copy the data. Without the unrolling, it will reduce the speed since the next store instruction for the same register using from the load will stall the pipeline. If the size of copy is too small for unrolled copy perform regular word copy. At last, copying the remainder in one byte at a time. The motivation to create the patch was to improve network performance on beaglev beta board. By observing with perf, the memcpy and __asm_copy_to_user had heavy cpu usage and the network speed was limited at around 680Mbps on 1Gbps lan. Typical network applications use system calls with a large buffer on send/recv() and sendto/recvfrom() for the optimization. The bench result, when patching only copy_user. The memcpy is without Matteo's patches but listing the both since they are the top two largest overhead. All results are from the same base kernel, same rootfs and same BeagleV beta board. Results of iperf3 have speedup on UDP with the copy_user patch alone. --- UDP send --- 306 Mbits/sec 362 Mbits/sec 305 Mbits/sec 362 Mbits/sec --- UDP recv --- 772 Mbits/sec 787 Mbits/sec 773 Mbits/sec 784 Mbits/sec Comparison by "perf top -Ue task-clock" while running iperf3. --- TCP recv --- * Before 40.40% [kernel] [k] memcpy 33.09% [kernel] [k] __asm_copy_to_user * With patch 50.35% [kernel] [k] memcpy 13.76% [kernel] [k] __asm_copy_to_user --- TCP send --- * Before 19.96% [kernel] [k] memcpy 9.84% [kernel] [k] __asm_copy_to_user * With patch 14.27% [kernel] [k] memcpy 7.37% [kernel] [k] __asm_copy_to_user --- UDP recv --- * Before 44.45% [kernel] [k] memcpy 31.04% [kernel] [k] __asm_copy_to_user * With patch 55.62% [kernel] [k] memcpy 11.22% [kernel] [k] __asm_copy_to_user --- UDP send --- * Before 25.18% [kernel] [k] memcpy 22.50% [kernel] [k] __asm_copy_to_user * With patch 28.90% [kernel] [k] memcpy 9.49% [kernel] [k] __asm_copy_to_user Signed-off-by: Akira Tsukamoto <akira.tsukamoto@gmail.com>
mcd500
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Hmm.. but your old version [1] is already in 5.14-rc1, so I think it's better just have a patch that fixes that code rather than 2 patches, one to revert and one to apply the fixed version. I'll wait for the replies on linux-riscv though. 1: ca6eaaa ("riscv: __asm_copy_to-from_user: Optimize unaligned memory access and pipeline stall") |
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I will drop this PR. Guenter and Geert reported has bug on rv32. I will make the patch against 5.14-rc* next time once spotting the fix on rv32. |
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A fstrim on a degraded raid1 can trigger the following null pointer dereference: BTRFS info (device loop0): allowing degraded mounts BTRFS info (device loop0): disk space caching is enabled BTRFS info (device loop0): has skinny extents BTRFS warning (device loop0): devid 2 uuid 97ac16f7-e14d-4db1-95bc-3d489b424adb is missing BTRFS warning (device loop0): devid 2 uuid 97ac16f7-e14d-4db1-95bc-3d489b424adb is missing BTRFS info (device loop0): enabling ssd optimizations BUG: kernel NULL pointer dereference, address: 0000000000000620 PGD 0 P4D 0 Oops: 0000 [#1] SMP NOPTI CPU: 0 PID: 4574 Comm: fstrim Not tainted 5.13.0-rc7+ #31 Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006 RIP: 0010:btrfs_trim_fs+0x199/0x4a0 [btrfs] RSP: 0018:ffff959541797d28 EFLAGS: 00010293 RAX: 0000000000000000 RBX: ffff946f84eca508 RCX: a7a67937adff8608 RDX: ffff946e8122d000 RSI: 0000000000000000 RDI: ffffffffc02fdbf0 RBP: ffff946ea4615000 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: ffff946e8122d960 R12: 0000000000000000 R13: ffff959541797db8 R14: ffff946e8122d000 R15: ffff959541797db8 FS: 00007f55917a5080(0000) GS:ffff946f9bc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000620 CR3: 000000002d2c8001 CR4: 00000000000706f0 Call Trace: btrfs_ioctl_fitrim+0x167/0x260 [btrfs] btrfs_ioctl+0x1c00/0x2fe0 [btrfs] ? selinux_file_ioctl+0x140/0x240 ? syscall_trace_enter.constprop.0+0x188/0x240 ? __x64_sys_ioctl+0x83/0xb0 __x64_sys_ioctl+0x83/0xb0 Reproducer: $ mkfs.btrfs -fq -d raid1 -m raid1 /dev/loop0 /dev/loop1 $ mount /dev/loop0 /btrfs $ umount /btrfs $ btrfs dev scan --forget $ mount -o degraded /dev/loop0 /btrfs $ fstrim /btrfs The reason is we call btrfs_trim_free_extents() for the missing device, which uses device->bdev (NULL for missing device) to find if the device supports discard. Fix is to check if the device is missing before calling btrfs_trim_free_extents(). CC: stable@vger.kernel.org # 5.4+ Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Anand Jain <anand.jain@oracle.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
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commit 16a200f upstream. A fstrim on a degraded raid1 can trigger the following null pointer dereference: BTRFS info (device loop0): allowing degraded mounts BTRFS info (device loop0): disk space caching is enabled BTRFS info (device loop0): has skinny extents BTRFS warning (device loop0): devid 2 uuid 97ac16f7-e14d-4db1-95bc-3d489b424adb is missing BTRFS warning (device loop0): devid 2 uuid 97ac16f7-e14d-4db1-95bc-3d489b424adb is missing BTRFS info (device loop0): enabling ssd optimizations BUG: kernel NULL pointer dereference, address: 0000000000000620 PGD 0 P4D 0 Oops: 0000 [#1] SMP NOPTI CPU: 0 PID: 4574 Comm: fstrim Not tainted 5.13.0-rc7+ #31 Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006 RIP: 0010:btrfs_trim_fs+0x199/0x4a0 [btrfs] RSP: 0018:ffff959541797d28 EFLAGS: 00010293 RAX: 0000000000000000 RBX: ffff946f84eca508 RCX: a7a67937adff8608 RDX: ffff946e8122d000 RSI: 0000000000000000 RDI: ffffffffc02fdbf0 RBP: ffff946ea4615000 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: ffff946e8122d960 R12: 0000000000000000 R13: ffff959541797db8 R14: ffff946e8122d000 R15: ffff959541797db8 FS: 00007f55917a5080(0000) GS:ffff946f9bc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000620 CR3: 000000002d2c8001 CR4: 00000000000706f0 Call Trace: btrfs_ioctl_fitrim+0x167/0x260 [btrfs] btrfs_ioctl+0x1c00/0x2fe0 [btrfs] ? selinux_file_ioctl+0x140/0x240 ? syscall_trace_enter.constprop.0+0x188/0x240 ? __x64_sys_ioctl+0x83/0xb0 __x64_sys_ioctl+0x83/0xb0 Reproducer: $ mkfs.btrfs -fq -d raid1 -m raid1 /dev/loop0 /dev/loop1 $ mount /dev/loop0 /btrfs $ umount /btrfs $ btrfs dev scan --forget $ mount -o degraded /dev/loop0 /btrfs $ fstrim /btrfs The reason is we call btrfs_trim_free_extents() for the missing device, which uses device->bdev (NULL for missing device) to find if the device supports discard. Fix is to check if the device is missing before calling btrfs_trim_free_extents(). CC: stable@vger.kernel.org # 5.4+ Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Anand Jain <anand.jain@oracle.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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[ Upstream commit 240e126 ] uart_handle_dcd_change() requires a port lock to be held and will emit a warning when lockdep is enabled. Held corresponding lock to fix the following warnings. [ 132.528648] WARNING: CPU: 5 PID: 11600 at drivers/tty/serial/serial_core.c:3046 uart_handle_dcd_change+0xf4/0x120 [ 132.530482] Modules linked in: [ 132.531050] CPU: 5 PID: 11600 Comm: jsm Not tainted 5.14.0-rc1-00003-g7fef2edf7cc7-dirty #31 [ 132.535268] RIP: 0010:uart_handle_dcd_change+0xf4/0x120 [ 132.557100] Call Trace: [ 132.557562] ? __free_pages+0x83/0xb0 [ 132.558213] neo_parse_modem+0x156/0x220 [ 132.558897] neo_param+0x399/0x840 [ 132.559495] jsm_tty_open+0x12f/0x2d0 [ 132.560131] uart_startup.part.18+0x153/0x340 [ 132.560888] ? lock_is_held_type+0xe9/0x140 [ 132.561660] uart_port_activate+0x7f/0xe0 [ 132.562351] ? uart_startup.part.18+0x340/0x340 [ 132.563003] tty_port_open+0x8d/0xf0 [ 132.563523] ? uart_set_options+0x1e0/0x1e0 [ 132.564125] uart_open+0x24/0x40 [ 132.564604] tty_open+0x15c/0x630 Signed-off-by: Zheyu Ma <zheyuma97@gmail.com> Link: https://lore.kernel.org/r/1626242003-3809-1-git-send-email-zheyuma97@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit d412137 ] The perf_buffer fails on system with offline cpus: # test_progs -t perf_buffer test_perf_buffer:PASS:nr_cpus 0 nsec test_perf_buffer:PASS:nr_on_cpus 0 nsec test_perf_buffer:PASS:skel_load 0 nsec test_perf_buffer:PASS:attach_kprobe 0 nsec test_perf_buffer:PASS:perf_buf__new 0 nsec test_perf_buffer:PASS:epoll_fd 0 nsec skipping offline CPU #24 skipping offline CPU #25 skipping offline CPU #26 skipping offline CPU #27 skipping offline CPU #28 skipping offline CPU #29 skipping offline CPU #30 skipping offline CPU #31 test_perf_buffer:PASS:perf_buffer__poll 0 nsec test_perf_buffer:PASS:seen_cpu_cnt 0 nsec test_perf_buffer:FAIL:buf_cnt got 24, expected 32 Summary: 0/0 PASSED, 0 SKIPPED, 1 FAILED Changing the test to check online cpus instead of possible. Signed-off-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: John Fastabend <john.fastabend@gmail.com> Link: https://lore.kernel.org/bpf/20211021114132.8196-2-jolsa@kernel.org Signed-off-by: Sasha Levin <sashal@kernel.org>
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The below crash can be encountered when using xdpsock in rx mode for legacy rq: the buffer gets released in the XDP_REDIRECT path, and then once again in the driver. This fix sets the flag to avoid releasing on the driver side. XSK handling of buffers for legacy rq was relying on the caller to set the skip release flag. But the referenced fix started using fragment counts for pages instead of the skip flag. Crash log: general protection fault, probably for non-canonical address 0xffff8881217e3a: 0000 [#1] SMP CPU: 0 PID: 14 Comm: ksoftirqd/0 Not tainted 6.5.0-rc1+ #31 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 RIP: 0010:bpf_prog_03b13f331978c78c+0xf/0x28 Code: ... RSP: 0018:ffff88810082fc98 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff888138404901 RCX: c0ffffc900027cbc RDX: ffffffffa000b514 RSI: 00ffff8881217e32 RDI: ffff888138404901 RBP: ffff88810082fc98 R08: 0000000000091100 R09: 0000000000000006 R10: 0000000000000800 R11: 0000000000000800 R12: ffffc9000027a000 R13: ffff8881217e2dc0 R14: ffff8881217e2910 R15: ffff8881217e2f00 FS: 0000000000000000(0000) GS:ffff88852c800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000564cb2e2cde0 CR3: 000000010e603004 CR4: 0000000000370eb0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> ? die_addr+0x32/0x80 ? exc_general_protection+0x192/0x390 ? asm_exc_general_protection+0x22/0x30 ? 0xffffffffa000b514 ? bpf_prog_03b13f331978c78c+0xf/0x28 mlx5e_xdp_handle+0x48/0x670 [mlx5_core] ? dev_gro_receive+0x3b5/0x6e0 mlx5e_xsk_skb_from_cqe_linear+0x6e/0x90 [mlx5_core] mlx5e_handle_rx_cqe+0x55/0x100 [mlx5_core] mlx5e_poll_rx_cq+0x87/0x6e0 [mlx5_core] mlx5e_napi_poll+0x45e/0x6b0 [mlx5_core] __napi_poll+0x25/0x1a0 net_rx_action+0x28a/0x300 __do_softirq+0xcd/0x279 ? sort_range+0x20/0x20 run_ksoftirqd+0x1a/0x20 smpboot_thread_fn+0xa2/0x130 kthread+0xc9/0xf0 ? kthread_complete_and_exit+0x20/0x20 ret_from_fork+0x1f/0x30 </TASK> Modules linked in: mlx5_ib mlx5_core rpcrdma rdma_ucm ib_iser libiscsi scsi_transport_iscsi ib_umad rdma_cm ib_ipoib iw_cm ib_cm ib_uverbs ib_core xt_conntrack xt_MASQUERADE nf_conntrack_netlink nfnetlink xt_addrtype iptable_nat nf_nat br_netfilter overlay zram zsmalloc fuse [last unloaded: mlx5_core] ---[ end trace 0000000000000000 ]--- Fixes: 7abd955 ("net/mlx5e: RX, Fix page_pool page fragment tracking for XDP") Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com> Reviewed-by: Tariq Toukan <tariqt@nvidia.com> Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
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syzkaller reported an overflown write in arp_req_get(). [0] When ioctl(SIOCGARP) is issued, arp_req_get() looks up an neighbour entry and copies neigh->ha to struct arpreq.arp_ha.sa_data. The arp_ha here is struct sockaddr, not struct sockaddr_storage, so the sa_data buffer is just 14 bytes. In the splat below, 2 bytes are overflown to the next int field, arp_flags. We initialise the field just after the memcpy(), so it's not a problem. However, when dev->addr_len is greater than 22 (e.g. MAX_ADDR_LEN), arp_netmask is overwritten, which could be set as htonl(0xFFFFFFFFUL) in arp_ioctl() before calling arp_req_get(). To avoid the overflow, let's limit the max length of memcpy(). Note that commit b5f0de6 ("net: dev: Convert sa_data to flexible array in struct sockaddr") just silenced syzkaller. [0]: memcpy: detected field-spanning write (size 16) of single field "r->arp_ha.sa_data" at net/ipv4/arp.c:1128 (size 14) WARNING: CPU: 0 PID: 144638 at net/ipv4/arp.c:1128 arp_req_get+0x411/0x4a0 net/ipv4/arp.c:1128 Modules linked in: CPU: 0 PID: 144638 Comm: syz-executor.4 Not tainted 6.1.74 #31 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-debian-1.16.0-5 04/01/2014 RIP: 0010:arp_req_get+0x411/0x4a0 net/ipv4/arp.c:1128 Code: fd ff ff e8 41 42 de fb b9 0e 00 00 00 4c 89 fe 48 c7 c2 20 6d ab 87 48 c7 c7 80 6d ab 87 c6 05 25 af 72 04 01 e8 5f 8d ad fb <0f> 0b e9 6c fd ff ff e8 13 42 de fb be 03 00 00 00 4c 89 e7 e8 a6 RSP: 0018:ffffc900050b7998 EFLAGS: 00010286 RAX: 0000000000000000 RBX: ffff88803a815000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff8641a44a RDI: 0000000000000001 RBP: ffffc900050b7a98 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 203a7970636d656d R12: ffff888039c54000 R13: 1ffff92000a16f37 R14: ffff88803a815084 R15: 0000000000000010 FS: 00007f172bf306c0(0000) GS:ffff88805aa00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f172b3569f0 CR3: 0000000057f12005 CR4: 0000000000770ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 PKRU: 55555554 Call Trace: <TASK> arp_ioctl+0x33f/0x4b0 net/ipv4/arp.c:1261 inet_ioctl+0x314/0x3a0 net/ipv4/af_inet.c:981 sock_do_ioctl+0xdf/0x260 net/socket.c:1204 sock_ioctl+0x3ef/0x650 net/socket.c:1321 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __x64_sys_ioctl+0x18e/0x220 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x37/0x90 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x64/0xce RIP: 0033:0x7f172b262b8d Code: 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f172bf300b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f172b3abf80 RCX: 00007f172b262b8d RDX: 0000000020000000 RSI: 0000000000008954 RDI: 0000000000000003 RBP: 00007f172b2d3493 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 000000000000000b R14: 00007f172b3abf80 R15: 00007f172bf10000 </TASK> Reported-by: syzkaller <syzkaller@googlegroups.com> Reported-by: Bjoern Doebel <doebel@amazon.de> Fixes: 1da177e ("Linux-2.6.12-rc2") Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Link: https://lore.kernel.org/r/20240215230516.31330-1-kuniyu@amazon.com Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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The current implementation of the mov instruction with sign extension has the
following problems:
1. It clobbers the source register if it is not stacked because it
sign extends the source and then moves it to the destination.
2. If the dst_reg is stacked, the current code doesn't write the value
back in case of 64-bit mov.
3. There is room for improvement by emitting fewer instructions.
The steps for fixing this and the instructions emitted by the JIT are explained
below with examples in all combinations:
Case A: offset == 32:
=====================
Case A.1: src and dst are stacked registers:
--------------------------------------------
1. Load src_lo into tmp_lo
2. Store tmp_lo into dst_lo
3. Sign extend tmp_lo into tmp_hi
4. Store tmp_hi to dst_hi
Example: r3 = (s32)r3
r3 is a stacked register
ldr r6, [r11, #-16] // Load r3_lo into tmp_lo
// str to dst_lo is not emitted because src_lo == dst_lo
asr r7, r6, #31 // Sign extend tmp_lo into tmp_hi
str r7, [r11, #-12] // Store tmp_hi into r3_hi
Case A.2: src is stacked but dst is not:
----------------------------------------
1. Load src_lo into dst_lo
2. Sign extend dst_lo into dst_hi
Example: r6 = (s32)r3
r6 maps to {ARM_R5, ARM_R4} and r3 is stacked
ldr r4, [r11, #-16] // Load r3_lo into r6_lo
asr r5, r4, #31 // Sign extend r6_lo into r6_hi
Case A.3: src is not stacked but dst is stacked:
------------------------------------------------
1. Store src_lo into dst_lo
2. Sign extend src_lo into tmp_hi
3. Store tmp_hi to dst_hi
Example: r3 = (s32)r6
r3 is stacked and r6 maps to {ARM_R5, ARM_R4}
str r4, [r11, #-16] // Store r6_lo to r3_lo
asr r7, r4, #31 // Sign extend r6_lo into tmp_hi
str r7, [r11, #-12] // Store tmp_hi to dest_hi
Case A.4: Both src and dst are not stacked:
-------------------------------------------
1. Mov src_lo into dst_lo
2. Sign extend src_lo into dst_hi
Example: (bf) r6 = (s32)r6
r6 maps to {ARM_R5, ARM_R4}
// Mov not emitted because dst == src
asr r5, r4, #31 // Sign extend r6_lo into r6_hi
Case B: offset != 32:
=====================
Case B.1: src and dst are stacked registers:
--------------------------------------------
1. Load src_lo into tmp_lo
2. Sign extend tmp_lo according to offset.
3. Store tmp_lo into dst_lo
4. Sign extend tmp_lo into tmp_hi
5. Store tmp_hi to dst_hi
Example: r9 = (s8)r3
r9 and r3 are both stacked registers
ldr r6, [r11, #-16] // Load r3_lo into tmp_lo
lsl r6, r6, #24 // Sign extend tmp_lo
asr r6, r6, #24 // ..
str r6, [r11, #-56] // Store tmp_lo to r9_lo
asr r7, r6, #31 // Sign extend tmp_lo to tmp_hi
str r7, [r11, #-52] // Store tmp_hi to r9_hi
Case B.2: src is stacked but dst is not:
----------------------------------------
1. Load src_lo into dst_lo
2. Sign extend dst_lo according to offset.
3. Sign extend tmp_lo into dst_hi
Example: r6 = (s8)r3
r6 maps to {ARM_R5, ARM_R4} and r3 is stacked
ldr r4, [r11, #-16] // Load r3_lo to r6_lo
lsl r4, r4, #24 // Sign extend r6_lo
asr r4, r4, #24 // ..
asr r5, r4, #31 // Sign extend r6_lo into r6_hi
Case B.3: src is not stacked but dst is stacked:
------------------------------------------------
1. Sign extend src_lo into tmp_lo according to offset.
2. Store tmp_lo into dst_lo.
3. Sign extend src_lo into tmp_hi.
4. Store tmp_hi to dst_hi.
Example: r3 = (s8)r1
r3 is stacked and r1 maps to {ARM_R3, ARM_R2}
lsl r6, r2, #24 // Sign extend r1_lo to tmp_lo
asr r6, r6, #24 // ..
str r6, [r11, #-16] // Store tmp_lo to r3_lo
asr r7, r6, #31 // Sign extend tmp_lo to tmp_hi
str r7, [r11, #-12] // Store tmp_hi to r3_hi
Case B.4: Both src and dst are not stacked:
-------------------------------------------
1. Sign extend src_lo into dst_lo according to offset.
2. Sign extend dst_lo into dst_hi.
Example: r6 = (s8)r1
r6 maps to {ARM_R5, ARM_R4} and r1 maps to {ARM_R3, ARM_R2}
lsl r4, r2, #24 // Sign extend r1_lo to r6_lo
asr r4, r4, #24 // ..
asr r5, r4, #31 // Sign extend r6_lo to r6_hi
Fixes: fc83265 ("arm32, bpf: add support for sign-extension mov instruction")
Reported-by: syzbot+186522670e6722692d86@syzkaller.appspotmail.com
Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Closes: https://lore.kernel.org/all/000000000000e9a8d80615163f2a@google.com
Link: https://lore.kernel.org/bpf/20240419182832.27707-1-puranjay@kernel.org
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This PR fixes the overrunning copy when the size is in the between 8SZREG and 9SZREG which was reported at linux-riscv mailing lists by Guenter, Geert and Qiu.
The links to their comments.
https://lists.infradead.org/pipermail/linux-riscv/2021-July/007504.html
https://lists.infradead.org/pipermail/linux-riscv/2021-July/007529.html
https://lists.infradead.org/pipermail/linux-riscv/2021-July/007579.html
This patch replaces my original patch and Qiu's fix.