From: Miklos Szeredi Date: Wed, 4 Aug 2021 11:22:58 +0000 (+0200) Subject: fuse: fix use after free in fuse_read_interrupt() X-Git-Tag: v5.15~343^2~8 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=e1e71c168813564be0f6ea3d6740a059ca42d177;p=platform%2Fkernel%2Flinux-starfive.git 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 Signed-off-by: Miklos Szeredi --- diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c index 1c8f79b..dde341a 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);