In the Linux kernel, the following vulnerability has been resolved:

ice: fix Rx page leak on multi-buffer frames

The iceputrxmbuf() function handles calling iceputrxbuf() for each buffer in the current frame. This function was introduced as part of handling multi-buffer XDP support in the ice driver.

It works by iterating over the buffers from firstdesc up to 1 plus the total number of fragments in the frame, cached from before the XDP program was executed.

If the hardware posts a descriptor with a size of 0, the logic used in iceputrxmbuf() breaks. Such descriptors get skipped and don't get added as fragments in iceaddxdpfrag. Since the buffer isn't counted as a fragment, we do not iterate over it in iceputrxmbuf(), and thus we don't call iceputrxbuf().

Because we don't call iceputrxbuf(), we don't attempt to re-use the page or free it. This leaves a stale page in the ring, as we don't increment nexttoalloc.

The icereuserxpage() assumes that the nexttoalloc has been incremented properly, and that it always points to a buffer with a NULL page. Since this function doesn't check, it will happily recycle a page over the top of the nexttoalloc buffer, losing track of the old page.

Note that this leak only occurs for multi-buffer frames. The iceputrxmbuf() function always handles at least one buffer, so a single-buffer frame will always get handled correctly. It is not clear precisely why the hardware hands us descriptors with a size of 0 sometimes, but it happens somewhat regularly with "jumbo frames" used by 9K MTU.

To fix iceputrxmbuf(), we need to make sure to call iceputrxbuf() on all buffers between firstdesc and nexttoclean. Borrow the logic of a similar function in i40e used for this same purpose. Use the same logic also in icegetpgcnts().

Instead of iterating over just the number of fragments, use a loop which iterates until the current index reaches to the nexttoclean element just past the current frame. Unlike i40e, the iceputrxmbuf() function does call iceputrxbuf() on the last buffer of the frame indicating the end of packet.

For non-linear (multi-buffer) frames, we need to take care when adjusting the pagecntbias. An XDP program might release fragments from the tail of the frame, in which case that fragment page is already released. Only update the pagecntbias for the first descriptor and fragments still remaining post-XDP program. Take care to only access the shared info for fragmented buffers, as this avoids a significant cache miss.

The xdpxmit value only needs to be updated if an XDP program is run, and only once per packet. Drop the xdpxmit pointer argument from iceputrxmbuf(). Instead, set xdpxmit in the icecleanrxirq() function directly. This avoids needing to pass the argument and avoids an extra bit-wise OR for each buffer in the frame.

Move the increment of the ntc local variable to ensure its updated before all calls to icegetpgcnts() or iceputrxmbuf(), as the loop logic requires the index of the element just after the current frame.

Now that we use an index pointer in the ring to identify the packet, we no longer need to track or cache the number of fragments in the rxring.

In the Linux kernel, the following vulnerability has been resolved:

NFSD: Protect against send buffer overflow in NFSv2 READ

Since before the git era, NFSD has conserved the number of pages held by each nfsd thread by combining the RPC receive and send buffers into a single array of pages. This works because there are no cases where an operation needs a large RPC Call message and a large RPC Reply at the same time.

Once an RPC Call has been received, svcprocess() updates svcrqst::rqres to describe the part of rqpages that can be used for constructing the Reply. This means that the send buffer (rqres) shrinks when the received RPC record containing the RPC Call is large.

A client can force this shrinkage on TCP by sending a correctly- formed RPC Call header contained in an RPC record that is excessively large. The full maximum payload size cannot be constructed in that case.

In the Linux kernel, the following vulnerability has been resolved:

tls: fix handling of zero-length records on the rxlist

Each recvmsg() call must process either - only contiguous DATA records (any number of them) - one non-DATA record

If the next record has different type than what has already been processed we break out of the main processing loop. If the record has already been decrypted (which may be the case for TLS 1.3 where we don't know type until decryption) we queue the pending record to the rxlist. Next recvmsg() will pick it up from there.

Queuing the skb to rxlist after zero-copy decrypt is not possible, since in that case we decrypted directly to the user space buffer, and we don't have an skb to queue (darg.skb points to the ciphertext skb for access to metadata like length).

Only data records are allowed zero-copy, and we break the processing loop after each non-data record. So we should never zero-copy and then find out that the record type has changed. The corner case we missed is when the initial record comes from rxlist, and it's zero length.

In the Linux kernel, the following vulnerability has been resolved:

netfilter: nfsetpipapoavx2: fix initial map fill

If the first field doesn't cover the entire start map, then we must zero out the remainder, else we leak those bits into the next match round map.

The early fix was incomplete and did only fix up the generic C implementation.

A followup patch adds a test case to nftconcatrange.sh.

In the Linux kernel, the following vulnerability has been resolved:

nfsd: clear aclaccess/acldefault after releasing them

If getting acldefault fails, aclaccess and acldefault will be released simultaneously. However, aclaccess will still retain a pointer pointing to the released posixacl, which will trigger a WARNING in nfs3svcreleasegetacl like this:

------------[ cut here ]------------ refcountt: underflow; use-after-free. WARNING: CPU: 26 PID: 3199 at lib/refcount.c:28 refcountwarnsaturate+0xb5/0x170 Modules linked in: CPU: 26 UID: 0 PID: 3199 Comm: nfsd Not tainted 6.12.0-rc6-00079-g04ae226af01f-dirty #8 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.1-2.fc37 04/01/2014 RIP: 0010:refcountwarnsaturate+0xb5/0x170 Code: cc cc 0f b6 1d b3 20 a5 03 80 fb 01 0f 87 65 48 d8 00 83 e3 01 75 e4 48 c7 c7 c0 3b 9b 85 c6 05 97 20 a5 03 01 e8 fb 3e 30 ff <0f> 0b eb cd 0f b6 1d 8a3 RSP: 0018:ffffc90008637cd8 EFLAGS: 00010282 RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff83904fde RDX: dffffc0000000000 RSI: 0000000000000008 RDI: ffff88871ed36380 RBP: ffff888158beeb40 R08: 0000000000000001 R09: fffff520010c6f56 R10: ffffc90008637ab7 R11: 0000000000000001 R12: 0000000000000001 R13: ffff888140e77400 R14: ffff888140e77408 R15: ffffffff858b42c0 FS: 0000000000000000(0000) GS:ffff88871ed00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000562384d32158 CR3: 000000055cc6a000 CR4: 00000000000006f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> ? refcountwarnsaturate+0xb5/0x170 ? warn+0xa5/0x140 ? refcountwarnsaturate+0xb5/0x170 ? reportbug+0x1b1/0x1e0 ? handlebug+0x53/0xa0 ? excinvalidop+0x17/0x40 ? asmexcinvalidop+0x1a/0x20 ? ticknohztickstopped+0x1e/0x40 ? refcountwarnsaturate+0xb5/0x170 ? refcountwarnsaturate+0xb5/0x170 nfs3svcreleasegetacl+0xc9/0xe0 svcprocesscommon+0x5db/0xb60 ? pfxsvcprocesscommon+0x10/0x10 ? rcureadunlock+0x69/0xa0 ? pfxnfsddispatch+0x10/0x10 ? svcxprtreceived+0xa1/0x120 ? xdrinitdecode+0x11d/0x190 svcprocess+0x2a7/0x330 svchandlexprt+0x69d/0x940 svcrecv+0x180/0x2d0 nfsd+0x168/0x200 ? pfxnfsd+0x10/0x10 kthread+0x1a2/0x1e0 ? kthread+0xf4/0x1e0 ? pfxkthread+0x10/0x10 retfromfork+0x34/0x60 ? pfxkthread+0x10/0x10 retfromforkasm+0x1a/0x30 </TASK> Kernel panic - not syncing: kernel: paniconwarn set ...

Clear aclaccess/acldefault after posixaclrelease is called to prevent UAF from being triggered.

In the Linux kernel, the following vulnerability has been resolved:

skbuff: fix coalescing for pagepool fragment recycling

Fix a use-after-free when using pagepool with page fragments. We encountered this problem during normal RX in the hns3 driver:

(1) Initially we have three descriptors in the RX queue. The first one allocates PAGE1 through pagepool, and the other two allocate one half of PAGE2 each. Page references look like this:

RXBD1 PAGE1 RXBD2 PAGE2 RXBD3 /

(2) Handle RX on the first descriptor. Allocate SKB1, eventually added to the receive queue by tcpqueuercv().

(3) Handle RX on the second descriptor. Allocate SKB2 and pass it to netifreceiveskb():

netifreceiveskb(SKB2) iprcv(SKB2) SKB3 = skbclone(SKB2)

SKB2 and SKB3 share a reference to PAGE2 through skbshinfo()->dataref. The other ref to PAGE2 is still held by RXBD3:

SKB2 ---+- PAGE2 SKB3 / / RXBD3 /

(3b) Now while handling TCP, coalesce SKB3 with SKB1:

tcpv4rcv(SKB3) tcptrycoalesce(to=SKB1, from=SKB3) // succeeds kfreeskbpartial(SKB3) skbreleasedata(SKB3) // drops one dataref

SKB1 PAGE1 \ SKB2 PAGE2 / RXBD3 /

In skbtrycoalesce(), skbfragref() takes a page reference to PAGE2, where it should instead have increased the pagepool frag reference, ppfragcount. Without coalescing, when releasing both SKB2 and SKB3, a single reference to PAGE2 would be dropped. Now when releasing SKB1 and SKB2, two references to PAGE2 will be dropped, resulting in underflow.

(3c) Drop SKB2:

afpacketrcv(SKB2) consumeskb(SKB2) skbreleasedata(SKB2) // drops second dataref pagepoolreturnskbpage(PAGE2) // drops one ppfragcount

SKB1 PAGE1 \ PAGE2 / RXBD3 /

(4) Userspace calls recvmsg() Copies SKB1 and releases it. Since SKB3 was coalesced with SKB1, we release the SKB3 page as well:

tcpeatrecvskb(SKB1) skbreleasedata(SKB1) pagepoolreturnskbpage(PAGE1) pagepoolreturnskbpage(PAGE2) // drops second ppfragcount

(5) PAGE2 is freed, but the third RX descriptor was still using it! In our case this causes IOMMU faults, but it would silently corrupt memory if the IOMMU was disabled.

Change the logic that checks whether pprecycle SKBs can be coalesced. We still reject differing pprecycle between 'from' and 'to' SKBs, but in order to avoid the situation described above, we also reject coalescing when both 'from' and 'to' are pprecycled and 'from' is cloned.

The new logic allows coalescing a cloned pprecycle SKB into a page refcounted one, because in this case the release (4) will drop the right reference, the one taken by skbtrycoalesce().