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| author |   Pavel Begunkov <asml.silence@gmail.com> | 2020-11-08 12:55:55 +0000 |
|---|---|---|
| committer |   Jens Axboe <axboe@kernel.dk> | 2020-12-09 12:03:59 -0700 |
| commit | 1a38ffc9cbca361cc274d6e234f5ef8922f0b6d9 (patch) | |
| tree | 708827385f3446a7507c2a9bb04411f05c013baf /fs/io_uring.c | |
| parent | io_uring: add timeout support for io_uring_enter() (diff) | |
| download | linux-dev-1a38ffc9cbca361cc274d6e234f5ef8922f0b6d9.tar.xz linux-dev-1a38ffc9cbca361cc274d6e234f5ef8922f0b6d9.zip | |
io_uring: NULL files dereference by SQPOLL
SQPOLL task may find sqo_task->files == NULL and
__io_sq_thread_acquire_files() would leave it unset, so following
fget_many() and others try to dereference NULL and fault. Propagate
an error files are missing.
[ 118.962785] BUG: kernel NULL pointer dereference, address:
0000000000000020
[ 118.963812] #PF: supervisor read access in kernel mode
[ 118.964534] #PF: error_code(0x0000) - not-present page
[ 118.969029] RIP: 0010:__fget_files+0xb/0x80
[ 119.005409] Call Trace:
[ 119.005651] fget_many+0x2b/0x30
[ 119.005964] io_file_get+0xcf/0x180
[ 119.006315] io_submit_sqes+0x3a4/0x950
[ 119.007481] io_sq_thread+0x1de/0x6a0
[ 119.007828] kthread+0x114/0x150
[ 119.008963] ret_from_fork+0x22/0x30
Reported-by: Josef Grieb <josef.grieb@gmail.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'fs/io_uring.c')
| -rw-r--r-- | fs/io_uring.c | 19 |
1 files changed, 12 insertions, 7 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c index ee25c70527aa..775a83ebc8ab 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -1061,7 +1061,7 @@ static void io_sq_thread_drop_mm_files(void) } } -static void __io_sq_thread_acquire_files(struct io_ring_ctx *ctx) +static int __io_sq_thread_acquire_files(struct io_ring_ctx *ctx) { if (!current->files) { struct files_struct *files; @@ -1071,7 +1071,7 @@ static void __io_sq_thread_acquire_files(struct io_ring_ctx *ctx) files = ctx->sqo_task->files; if (!files) { task_unlock(ctx->sqo_task); - return; + return -EOWNERDEAD; } atomic_inc(&files->count); get_nsproxy(ctx->sqo_task->nsproxy); @@ -1083,6 +1083,7 @@ static void __io_sq_thread_acquire_files(struct io_ring_ctx *ctx) current->nsproxy = nsproxy; task_unlock(current); } + return 0; } static int __io_sq_thread_acquire_mm(struct io_ring_ctx *ctx) @@ -1114,15 +1115,19 @@ static int io_sq_thread_acquire_mm_files(struct io_ring_ctx *ctx, struct io_kiocb *req) { const struct io_op_def *def = &io_op_defs[req->opcode]; + int ret; if (def->work_flags & IO_WQ_WORK_MM) { - int ret = __io_sq_thread_acquire_mm(ctx); + ret = __io_sq_thread_acquire_mm(ctx); if (unlikely(ret)) return ret; } - if (def->needs_file || (def->work_flags & IO_WQ_WORK_FILES)) - __io_sq_thread_acquire_files(ctx); + if (def->needs_file || (def->work_flags & IO_WQ_WORK_FILES)) { + ret = __io_sq_thread_acquire_files(ctx); + if (unlikely(ret)) + return ret; + } return 0; } @@ -2130,8 +2135,8 @@ static void __io_req_task_submit(struct io_kiocb *req) { struct io_ring_ctx *ctx = req->ctx; - if (!__io_sq_thread_acquire_mm(ctx)) { - __io_sq_thread_acquire_files(ctx); + if (!__io_sq_thread_acquire_mm(ctx) && + !__io_sq_thread_acquire_files(ctx)) { mutex_lock(&ctx->uring_lock); __io_queue_sqe(req, NULL); mutex_unlock(&ctx->uring_lock); |