From 51efca72345acdbedc4af76782d464bd15ba50ff Mon Sep 17 00:00:00 2001 From: Weiming Shi Date: Sun, 25 Oct 2026 02:07:30 -0700 Subject: [PATCH] smb: client: stop processing a read response after a receive error cifs_read_iter_from_socket() may call cifs_reconnect() before returning an error. The reconnect path aborts pending mids and invokes their callbacks. The callback can then release the cifs_io_subrequest containing rdata. cifs_readv_receive() nevertheless continues after a negative return and may dereference rdata in cifs_readv_discard(). KASAN reports the resulting UAF: BUG: KASAN: slab-use-after-free in cifs_readv_receive Read of size 4 by task cifsd cifs_readv_receive (fs/smb/client/transport.c:1284) cifs_demultiplex_thread (fs/smb/client/connect.c:1355) kthread (kernel/kthread.c:436) ret_from_fork (arch/x86/kernel/process.c:158) Freed by task 148: netfs_put_subrequest (fs/netfs/objects.c:267) netfs_read_collection (fs/netfs/read_collect.c:460) netfs_wait_for_in_progress (fs/netfs/misc.c:462) Return the socket error immediately, as this path did before the iterator conversion. This also avoids adding a negative length to total_read. Cc: stable@vger.kernel.org Fixes: d08089f649a0 ("cifs: Change the I/O paths to use an iterator rather than a page list") Reported-by: co+24c7c12d69e63c6d@bugs.sh Assisted-by: LLM Signed-off-by: Weiming Shi Signed-off-by: Paulo Alcantara --- fs/smb/client/transport.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/smb/client/transport.c b/fs/smb/client/transport.c index 60699d2799fb..d0d0159c1061 100644 --- a/fs/smb/client/transport.c +++ b/fs/smb/client/transport.c @@ -1345,6 +1345,8 @@ cifs_readv_receive(struct TCP_Server_Info *server, struct mid_q_entry *mid) #endif length = cifs_read_iter_from_socket(server, &rdata->subreq.io_iter, data_len); + if (length < 0) + return length; if (length > 0) rdata->got_bytes += length; server->total_read += length;