diff options
| author | Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com> | 2021-02-04 17:20:56 +0800 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2021-02-04 07:43:21 -0700 |
| commit | d7e10d47691d1702db1cd1edcc689d3031eefc67 (patch) | |
| tree | 053f3a2f608b59eff9f85ccca068124f7bdceddd | |
| parent | 3a7efd1ad269ccaf9c1423364d97c9661ba6dafa (diff) | |
io_uring: don't modify identity's files uncess identity is cowed
Abaci Robot reported following panic:
BUG: kernel NULL pointer dereference, address: 0000000000000000
PGD 800000010ef3f067 P4D 800000010ef3f067 PUD 10d9df067 PMD 0
Oops: 0002 [#1] SMP PTI
CPU: 0 PID: 1869 Comm: io_wqe_worker-0 Not tainted 5.11.0-rc3+ #1
Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
RIP: 0010:put_files_struct+0x1b/0x120
Code: 24 18 c7 00 f4 ff ff ff e9 4d fd ff ff 66 90 0f 1f 44 00 00 41 57 41 56 49 89 fe 41 55 41 54 55 53 48 83 ec 08 e8 b5 6b db ff 41 ff 0e 74 13 48 83 c4 08 5b 5d 41 5c 41 5d 41 5e 41 5f e9 9c
RSP: 0000:ffffc90002147d48 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff88810d9a5300 RCX: 0000000000000000
RDX: ffff88810d87c280 RSI: ffffffff8144ba6b RDI: 0000000000000000
RBP: 0000000000000080 R08: 0000000000000001 R09: ffffffff81431500
R10: ffff8881001be000 R11: 0000000000000000 R12: ffff88810ac2f800
R13: ffff88810af38a00 R14: 0000000000000000 R15: ffff8881057130c0
FS: 0000000000000000(0000) GS:ffff88813bc00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000010dbaa002 CR4: 00000000003706f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
__io_clean_op+0x10c/0x2a0
io_dismantle_req+0x3c7/0x600
__io_free_req+0x34/0x280
io_put_req+0x63/0xb0
io_worker_handle_work+0x60e/0x830
? io_wqe_worker+0x135/0x520
io_wqe_worker+0x158/0x520
? __kthread_parkme+0x96/0xc0
? io_worker_handle_work+0x830/0x830
kthread+0x134/0x180
? kthread_create_worker_on_cpu+0x90/0x90
ret_from_fork+0x1f/0x30
Modules linked in:
CR2: 0000000000000000
---[ end trace c358ca86af95b1e7 ]---
I guess case below can trigger above panic: there're two threads which
operates different io_uring ctxs and share same sqthread identity, and
later one thread exits, io_uring_cancel_task_requests() will clear
task->io_uring->identity->files to be NULL in sqpoll mode, then another
ctx that uses same identity will panic.
Indeed we don't need to clear task->io_uring->identity->files here,
io_grab_identity() should handle identity->files changes well, if
task->io_uring->identity->files is not equal to current->files,
io_cow_identity() should handle this changes well.
Cc: stable@vger.kernel.org # 5.5+
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Xiaoguang Wang <xiaoguang.wang@linux.alibaba.com>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | fs/io_uring.c | 6 |
1 files changed, 0 insertions, 6 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c index 38c6cbe1ab38..5d3348d66f06 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -8982,12 +8982,6 @@ static void io_uring_cancel_task_requests(struct io_ring_ctx *ctx, if ((ctx->flags & IORING_SETUP_SQPOLL) && ctx->sq_data) { atomic_dec(&task->io_uring->in_idle); - /* - * If the files that are going away are the ones in the thread - * identity, clear them out. - */ - if (task->io_uring->identity->files == files) - task->io_uring->identity->files = NULL; io_sq_thread_unpark(ctx->sq_data); } } |