* [PATCH AUTOSEL 5.13 05/29] fuse: fix use after free in fuse_read_interrupt()
[not found] <20210911131233.284800-1-sashal@kernel.org>
@ 2021-09-11 13:12 ` Sasha Levin
0 siblings, 0 replies; only message in thread
From: Sasha Levin @ 2021-09-11 13:12 UTC (permalink / raw)
To: linux-kernel, stable; +Cc: Miklos Szeredi, lijiazi, Sasha Levin, linux-fsdevel
From: Miklos Szeredi <mszeredi@redhat.com>
[ Upstream commit e1e71c168813564be0f6ea3d6740a059ca42d177 ]
There is a potential race between fuse_read_interrupt() and
fuse_request_end().
TASK1
in fuse_read_interrupt(): delete req->intr_entry (while holding
fiq->lock)
TASK2
in fuse_request_end(): req->intr_entry is empty -> skip fiq->lock
wake up TASK3
TASK3
request is freed
TASK1
in fuse_read_interrupt(): dereference req->in.h.unique ***BAM***
Fix by always grabbing fiq->lock if the request was ever interrupted
(FR_INTERRUPTED set) thereby serializing with concurrent
fuse_read_interrupt() calls.
FR_INTERRUPTED is set before the request is queued on fiq->interrupts.
Dequeing the request is done with list_del_init() but FR_INTERRUPTED is not
cleared in this case.
Reported-by: lijiazi <lijiazi@xiaomi.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/fuse/dev.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index b8d58aa08206..339ebd3ab4f2 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -288,10 +288,10 @@ void fuse_request_end(struct fuse_req *req)
/*
* test_and_set_bit() implies smp_mb() between bit
- * changing and below intr_entry check. Pairs with
+ * changing and below FR_INTERRUPTED check. Pairs with
* smp_mb() from queue_interrupt().
*/
- if (!list_empty(&req->intr_entry)) {
+ if (test_bit(FR_INTERRUPTED, &req->flags)) {
spin_lock(&fiq->lock);
list_del_init(&req->intr_entry);
spin_unlock(&fiq->lock);
--
2.30.2
^ permalink raw reply related [flat|nested] only message in thread
only message in thread, other threads:[~2021-09-11 13:14 UTC | newest]
Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
[not found] <20210911131233.284800-1-sashal@kernel.org>
2021-09-11 13:12 ` [PATCH AUTOSEL 5.13 05/29] fuse: fix use after free in fuse_read_interrupt() Sasha Levin
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).