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authorMiklos Szeredi <mszeredi@redhat.com>2021-08-04 13:22:58 +0200
committerMiklos Szeredi <mszeredi@redhat.com>2021-08-04 13:22:58 +0200
commite1e71c168813564be0f6ea3d6740a059ca42d177 (patch)
treefae8cc56016feb9703453a553229b4161d62e49f /fs/fuse
parente73f0f0ee7541171d89f2e2491130c7771ba58d3 (diff)
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.c4
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);