CVE-2026-72339: qede: fix off-by-one in BD ring consumption on build_skb failure

CVE-2026-72339: qede: fix off-by-one in BD ring consumption on build_skb failure

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

Description
===========

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

qede: fix off-by-one in BD ring consumption on build_skb failure

qede_rx_build_skb() and qede_tpa_rx_build_skb() do not check for a
NULL return from qede_build_skb(). When it returns NULL under memory
pressure, the functions still consume a BD from the ring before
returning NULL. The callers then recycle additional BDs, resulting in
one extra BD being consumed (off-by-one). This desynchronizes the BD
ring, which can corrupt DMA page reference counts and lead to SLUB
freelist corruption.

Commit 4e910dbe3650 ("qede: confirm skb is allocated before using")
added a NULL check inside qede_build_skb() to prevent a NULL pointer
dereference, but did not address the missing NULL checks in the
callers, making this off-by-one reachable.

Fix this by adding NULL checks for the return value of
qede_build_skb() in both qede_rx_build_skb() and
qede_tpa_rx_build_skb(), returning NULL immediately before any BD ring
manipulation.

The Linux kernel CVE team has assigned CVE-2026-72339 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 4.18 with commit 8a8633978b842c88fbcfe00d4e5dde96048f630e and fixed in 5.10.261 with commit ecc05d4b20220a09c9c69584fc46ca55248a374a
	Issue introduced in 4.18 with commit 8a8633978b842c88fbcfe00d4e5dde96048f630e and fixed in 5.15.212 with commit 07be8b8adf91b7ada4c3dacce064d572a6066421
	Issue introduced in 4.18 with commit 8a8633978b842c88fbcfe00d4e5dde96048f630e and fixed in 6.1.178 with commit 1624aa100c0b218181aa74e3696a389b509298cb
	Issue introduced in 4.18 with commit 8a8633978b842c88fbcfe00d4e5dde96048f630e and fixed in 6.6.145 with commit 0bf78df2d3ecb1f4964ff42a7327d25845955153
	Issue introduced in 4.18 with commit 8a8633978b842c88fbcfe00d4e5dde96048f630e and fixed in 6.12.97 with commit 814a5edac8c9fc04051808d5faaa93768e989281
	Issue introduced in 4.18 with commit 8a8633978b842c88fbcfe00d4e5dde96048f630e and fixed in 6.18.40 with commit b066420e57f3402a52c998678b4678252ac9bb63
	Issue introduced in 4.18 with commit 8a8633978b842c88fbcfe00d4e5dde96048f630e and fixed in 7.1.5 with commit 982d6d6bc059c5dff37a2201c2f08c14bcfcbd20
	Issue introduced in 4.18 with commit 8a8633978b842c88fbcfe00d4e5dde96048f630e and fixed in 7.2-rc3 with commit a0a558ca7e75b49e71f8c545c30e8c005e6e4e2f

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-72339
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	drivers/net/ethernet/qlogic/qede/qede_fp.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/ecc05d4b20220a09c9c69584fc46ca55248a374a
	https://git.kernel.org/stable/c/07be8b8adf91b7ada4c3dacce064d572a6066421
	https://git.kernel.org/stable/c/1624aa100c0b218181aa74e3696a389b509298cb
	https://git.kernel.org/stable/c/0bf78df2d3ecb1f4964ff42a7327d25845955153
	https://git.kernel.org/stable/c/814a5edac8c9fc04051808d5faaa93768e989281
	https://git.kernel.org/stable/c/b066420e57f3402a52c998678b4678252ac9bb63
	https://git.kernel.org/stable/c/982d6d6bc059c5dff37a2201c2f08c14bcfcbd20
	https://git.kernel.org/stable/c/a0a558ca7e75b49e71f8c545c30e8c005e6e4e2f