kernel/git/stable/linux.git/net/rxrpc/recvmsg.c, branch linux-7.2.y

rxrpc: Fix leak of released call in recvmsg(MSG_PEEK)

2026-06-25T17:07:19+00:00

Fix rxrpc_recvmsg() to also drop the ref it holds on an already-released call if MSG_PEEK is in force (the function holds a ref on the call irrespective of whether MSG_PEEK is specified or not). Fixes: 962fb1f651c2 ("rxrpc: Fix recv-recv race of completed call") Link: https://sashiko.dev/#/patchset/20260616155749.2125907-1-dhowells%40redhat.com Signed-off-by: David Howells cc: Marc Dionne cc: Jeffrey Altman cc: Simon Horman cc: linux-afs@lists.infradead.org cc: stable@kernel.org Link: https://patch.msgid.link/20260624163819.3017002-11-dhowells@redhat.com Signed-off-by: Jakub Kicinski

rxrpc: Fix socket notification race

2026-06-25T17:07:19+00:00

There's a race between rxrpc_recvmsg() and rxrpc_notify_socket(), whereby the latter's attempt to avoid disabling interrupts and taking the socket's recvmsg_lock if the call is already queued may happen simultaneously with the former's discarding of a call that has nothing queued. Fix this by removing the shortcut. Note that this only affects userspace's use of AF_RXRPC; the AFS filesystem driver doesn't use the socket queue. Fixes: 248f219cb8bc ("rxrpc: Rewrite the data and ack handling code") Link: https://sashiko.dev/#/patchset/20260616155749.2125907-1-dhowells%40redhat.com Signed-off-by: David Howells cc: Marc Dionne cc: Jeffrey Altman cc: Simon Horman cc: linux-afs@lists.infradead.org cc: stable@kernel.org Link: https://patch.msgid.link/20260624163819.3017002-10-dhowells@redhat.com Signed-off-by: Jakub Kicinski

rxrpc: Fix potential infinite loop in rxrpc_recvmsg()

2026-06-25T17:07:18+00:00

Fix the wait in rxrpc_recvmsg() also take check the oob queue. Fixes: 5800b1cf3fd8 ("rxrpc: Allow CHALLENGEs to the passed to the app for a RESPONSE") Link: https://sashiko.dev/#/patchset/20260616155749.2125907-1-dhowells%40redhat.com Signed-off-by: David Howells cc: Marc Dionne cc: Jeffrey Altman cc: Simon Horman cc: linux-afs@lists.infradead.org cc: stable@kernel.org Link: https://patch.msgid.link/20260624163819.3017002-9-dhowells@redhat.com Signed-off-by: Jakub Kicinski

rxrpc: Fix double unlock in rxrpc_recvmsg()

2026-06-25T17:07:18+00:00

Fix a double unlock in rxrpc_recvmsg() when dealing with OOB messages. Fixes: 5800b1cf3fd8 ("rxrpc: Allow CHALLENGEs to the passed to the app for a RESPONSE") Link: https://sashiko.dev/#/patchset/20260609140911.838677-1-dhowells%40redhat.com Signed-off-by: David Howells cc: Marc Dionne cc: Simon Horman cc: linux-afs@lists.infradead.org cc: stable@kernel.org Link: https://patch.msgid.link/20260624163819.3017002-4-dhowells@redhat.com Signed-off-by: Jakub Kicinski

rxrpc: Don't move a peeked OOB message onto the pending queue

2026-06-12T23:48:54+00:00

rxrpc_recvmsg_oob() takes a received oob message off recvmsg_oobq and, if a response is needed, moves it onto the pending_oobq tree. However, only the unlink from recvmsg_oobq is guarded by MSG_PEEK; the move onto pending_oobq always runs. As a result, reading a challenge with MSG_PEEK leaves the skb on recvmsg_oobq while also adding it to pending_oobq. Since struct sk_buff's rbnode shares storage with its next and prev pointers, rb_insert_color() overwrites the list linkage, and the skb, which holds a single reference, becomes reachable from both queues at once. When the socket is closed both queues are drained in turn. While draining recvmsg_oobq, __skb_unlink() follows the next and prev pointers that rbnode has overwritten and writes to a bad address. Also, as the skb holds a single reference but is freed from each queue, both the skb and the connection reference it holds are released twice. This leads to memory corruption and to a use-after-free caused by the connection refcount underflow. MSG_PEEK does not consume the message from the queue, so only unlink it from recvmsg_oobq and then move it onto pending_oobq or free it when the message is actually consumed. Fixes: 5800b1cf3fd8 ("rxrpc: Allow CHALLENGEs to the passed to the app for a RESPONSE") Signed-off-by: Hyunwoo Kim Signed-off-by: David Howells cc: Marc Dionne cc: Simon Horman cc: linux-afs@lists.infradead.org cc: stable@kernel.org Link: https://patch.msgid.link/20260609140911.838677-3-dhowells@redhat.com Signed-off-by: Jakub Kicinski

rxrpc: rxrpc_verify_data ensure rx_dec_buffer alloc

2026-06-12T23:48:54+00:00

rxrpc_recvmsg_data() calls rxrpc_verify_data() whenever the rxrpc_call.rx_dec_buffer is unallocated and assumes that upon successful return that rx_dec_buffer must be allocated. However, rxrpc_verify_data() does not request an allocation if the rxrpc_skb_priv.len is zero. In addition, failure to allocate rx_dec_buffer will result in a call to skb_copy_bits() with a NULL destination which can trigger a NULL pointer dereference. To prevent these issues rxrpc_verify_data() is modified to always attempt to allocate the rxrpc_call.rx_dec_buffer if it is NULL. This issue was identified with assistance of a private sashiko instance. Fixes: d2bc90cf6c75cb ("rxrpc: Fix DATA decrypt vs splice() by copying data to buffer in recvmsg") Reported-by: Simon Horman Signed-off-by: Jeffrey Altman Signed-off-by: David Howells cc: Jiayuan Chen cc: Marc Dionne cc: linux-afs@lists.infradead.org cc: stable@kernel.org Link: https://patch.msgid.link/20260609140911.838677-2-dhowells@redhat.com Signed-off-by: Jakub Kicinski

rxrpc: Fix DATA decrypt vs splice() by copying data to buffer in recvmsg

2026-05-20T23:36:45+00:00

This improves the fix for CVE-2026-43500. Fix the pagecache corruption from in-place decryption of a DATA packet transmitted locally by splice() by getting rid of the packet sharing in the I/O thread and unconditionally extracting the packet content into a bounce buffer in which the buffer is decrypted. recvmsg() (or the kernel equivalent) then copies the data from the bounce buffer to the destination buffer. The sk_buff then remains unmodified. This has an additional advantage in that the packet is then arranged in the buffer with the correct alignment required for the crypto algorithms to process directly. The performance of the crypto does seem to be a little faster and, surprisingly, the unencrypted performance doesn't seem to change much - possibly due to removing complexity from the I/O thread. Yet another advantage is that the I/O thread doesn't have to copy packets which would slow down packet distribution, ACK generation, etc.. The buffer belongs to the call and is allocated initially at 2K, sufficiently large to hold a whole jumbo subpacket, but the buffer will be increased in size if needed. However, to take this work, MSG_PEEK may cause a later packet to be decrypted into the buffer, in which case the earlier one will need re-decrypting for a subsequent recvmsg(). Note that rx_pkt_offset may legitimately see 0 as a valid offset now, so switch to using USHRT_MAX to indicate an invalid offset. Note also that I would generally prefer to replace the buffers of the current sk_buff with a new kmalloc'd buffer of the right size, ditching the old data and frags as this makes the handling of MSG_PEEK easier and removes the re-decryption issue, but this looks like quite a complicated thing to achieve. skb_morph() looks half way to what I want, but I don't want to have to allocate a new sk_buff. Fixes: d0d5c0cd1e71 ("rxrpc: Use skb_unshare() rather than skb_cow_data()") Reported-by: Hyunwoo Kim Closes: https://lore.kernel.org/r/afKV2zGR6rrelPC7@v4bel/ Signed-off-by: David Howells cc: Simon Horman cc: Jiayuan Chen cc: linux-afs@lists.infradead.org Reviewed-by: Jeffrey Altman Tested-by: Marc Dionne Link: https://patch.msgid.link/20260515230516.2718212-3-dhowells@redhat.com Signed-off-by: Jakub Kicinski

rxrpc: Fix recvmsg() unconditional requeue

2026-01-19T18:07:06+00:00

If rxrpc_recvmsg() fails because MSG_DONTWAIT was specified but the call at the front of the recvmsg queue already has its mutex locked, it requeues the call - whether or not the call is already queued. The call may be on the queue because MSG_PEEK was also passed and so the call was not dequeued or because the I/O thread requeued it. The unconditional requeue may then corrupt the recvmsg queue, leading to things like UAFs or refcount underruns. Fix this by only requeuing the call if it isn't already on the queue - and moving it to the front if it is already queued. If we don't queue it, we have to put the ref we obtained by dequeuing it. Also, MSG_PEEK doesn't dequeue the call so shouldn't call rxrpc_notify_socket() for the call if we didn't use up all the data on the queue, so fix that also. Fixes: 540b1c48c37a ("rxrpc: Fix deadlock between call creation and sendmsg/recvmsg") Reported-by: Faith Reported-by: Pumpkin Chang Signed-off-by: David Howells Acked-by: Marc Dionne cc: Nir Ohfeld cc: Willy Tarreau cc: Simon Horman cc: linux-afs@lists.infradead.org cc: stable@kernel.org Link: https://patch.msgid.link/95163.1768428203@warthog.procyon.org.uk Signed-off-by: Jakub Kicinski

rxrpc: Fix notification vs call-release vs recvmsg

2025-07-17T14:50:48+00:00

When a call is released, rxrpc takes the spinlock and removes it from ->recvmsg_q in an effort to prevent racing recvmsg() invocations from seeing the same call. Now, rxrpc_recvmsg() only takes the spinlock when actually removing a call from the queue; it doesn't, however, take it in the lead up to that when it checks to see if the queue is empty. It *does* hold the socket lock, which prevents a recvmsg/recvmsg race - but this doesn't prevent sendmsg from ending the call because sendmsg() drops the socket lock and relies on the call->user_mutex. Fix this by firstly removing the bit in rxrpc_release_call() that dequeues the released call and, instead, rely on recvmsg() to simply discard released calls (done in a preceding fix). Secondly, rxrpc_notify_socket() is abandoned if the call is already marked as released rather than trying to be clever by setting both pointers in call->recvmsg_link to NULL to trick list_empty(). This isn't perfect and can still race, resulting in a released call on the queue, but recvmsg() will now clean that up. Fixes: 17926a79320a ("[AF_RXRPC]: Provide secure RxRPC sockets for use by userspace and kernel both") Signed-off-by: David Howells Reviewed-by: Jeffrey Altman cc: Marc Dionne cc: Junvyyang, Tencent Zhuque Lab cc: LePremierHomme cc: Simon Horman cc: linux-afs@lists.infradead.org Link: https://patch.msgid.link/20250717074350.3767366-4-dhowells@redhat.com Signed-off-by: Jakub Kicinski

rxrpc: Fix recv-recv race of completed call

2025-07-17T14:50:48+00:00

If a call receives an event (such as incoming data), the call gets placed on the socket's queue and a thread in recvmsg can be awakened to go and process it. Once the thread has picked up the call off of the queue, further events will cause it to be requeued, and once the socket lock is dropped (recvmsg uses call->user_mutex to allow the socket to be used in parallel), a second thread can come in and its recvmsg can pop the call off the socket queue again. In such a case, the first thread will be receiving stuff from the call and the second thread will be blocked on call->user_mutex. The first thread can, at this point, process both the event that it picked call for and the event that the second thread picked the call for and may see the call terminate - in which case the call will be "released", decoupling the call from the user call ID assigned to it (RXRPC_USER_CALL_ID in the control message). The first thread will return okay, but then the second thread will wake up holding the user_mutex and, if it sees that the call has been released by the first thread, it will BUG thusly: kernel BUG at net/rxrpc/recvmsg.c:474! Fix this by just dequeuing the call and ignoring it if it is seen to be already released. We can't tell userspace about it anyway as the user call ID has become stale. Fixes: 248f219cb8bc ("rxrpc: Rewrite the data and ack handling code") Reported-by: Junvyyang, Tencent Zhuque Lab Signed-off-by: David Howells Reviewed-by: Jeffrey Altman cc: LePremierHomme cc: Marc Dionne cc: Simon Horman cc: linux-afs@lists.infradead.org Link: https://patch.msgid.link/20250717074350.3767366-3-dhowells@redhat.com Signed-off-by: Jakub Kicinski