Minki/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2024-11-10 14:11:52 +00:00
Code Issues Packages Projects Releases Wiki Activity

io_uring: fix race condition reading SQ entries

Browse Source 
A read memory barrier is required between reading SQ tail and reading
the actual data belonging to the SQ entry.

Userspace needs a matching write barrier between writing SQ entries and
updating SQ tail (using smp_store_release to update tail will do).

Signed-off-by: Stefan Bühler <source@stbuehler.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Stefan Bühler 2019-04-19 11:57:44 +02:00 committed by Jens Axboe
parent 35fa71a030
commit e523a29c4f
1 changed files with 2 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
fs/io_uring.c
View File

@ -1739,7 +1739,8 @@ static bool io_get_sqring(struct io_ring_ctx *ctx, struct sqe_submit *s)
head = ctx->cached_sq_head;
/* See comment at the top of this file */
smp_rmb();
if (head == READ_ONCE(ring->r.tail))
/* make sure SQ entry isn't read before tail */
if (head == smp_load_acquire(&ring->r.tail))
return false;
head = READ_ONCE(ring->array[head & ctx->sq_mask]);