Bharath Vedartham wrote on Thu, May 23, 2019: > v9fs_cache_session_get_cookie assigns a random cachetag to > v9ses->cachetag, if the cachetag is not assigned previously. > > v9fs_random_cachetag allocates memory to v9ses->cachetag with kmalloc > and uses scnprintf to fill it up with a cachetag. > > But if scnprintf fails, v9ses->cachetag is not freed in the current code > causing a memory leak. > > Fix this by freeing v9ses->cachetag it v9fs_random_cachetag fails. > > This was reported by syzbot, the link to the report is below: > https://syzkaller.appspot.com/bug?id=f012bdf297a7a4c860c38a88b44fbee43fd9bbf3 > > Reported-by: syzbot+3a030a73b6c1e9833...@syzkaller.appspotmail.com > Signed-off-by: Bharath Vedartham <linux.b...@gmail.com> > --- > fs/9p/cache.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/fs/9p/cache.c b/fs/9p/cache.c > index 9eb3470..4463b91 100644 > --- a/fs/9p/cache.c > +++ b/fs/9p/cache.c > @@ -66,6 +66,7 @@ void v9fs_cache_session_get_cookie(struct v9fs_session_info > *v9ses) > if (!v9ses->cachetag) { > if (v9fs_random_cachetag(v9ses) < 0) { > v9ses->fscache = NULL; > + kfree(v9ses->cachetag);
I would also reset v9ses->cachetag to NULL just in case, v9fs_cache_session_get_cookie will use v9ses->cachetag as it is if it is not null and you were leaving an invalid pointer there I do not see any reason it could be called multiple times but v9fs_cache_session_get_cookie does not return any error (void function) so something later on could try to use that cachetag incorrectly later on Thanks, -- Dominique
