diff options
| author | Miklos Szeredi <mszeredi@redhat.com> | 2021-08-04 14:22:58 +0300 |
|---|---|---|
| committer | Miklos Szeredi <mszeredi@redhat.com> | 2021-08-04 14:22:58 +0300 |
| commit | e1e71c168813564be0f6ea3d6740a059ca42d177 (patch) | |
| tree | fae8cc56016feb9703453a553229b4161d62e49f /fs/fuse | |
| parent | e73f0f0ee7541171d89f2e2491130c7771ba58d3 (diff) | |
| download | linux-e1e71c168813564be0f6ea3d6740a059ca42d177.tar.xz | |
fuse: fix use after free in fuse_read_interrupt()
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>
Diffstat (limited to 'fs/fuse')
| -rw-r--r-- | fs/fuse/dev.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c index 1c8f79b3dd06..dde341a6388a 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); |