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

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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 4e910dbe36 ("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.

Fixes: 8a8633978b ("qede: Add build_skb() support.")
Signed-off-by: Shigeru Yoshida <syoshida@redhat.com>
Reviewed-by: Jamie Bainbridge <jamie.bainbridge@gmail.com>
Link: https://patch.msgid.link/20260630164623.3152625-1-syoshida@redhat.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Shigeru Yoshida
2026-07-01 01:46:20 +09:00
committed by Paolo Abeni
parent d7a8d500d7
commit a0a558ca7e
1 changed files with 5 additions and 0 deletions
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5
drivers/net/ethernet/qlogic/qede/qede_fp.c
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@@ -765,6 +765,9 @@ qede_tpa_rx_build_skb(struct qede_dev *edev,
struct sk_buff *skb;
skb = qede_build_skb(rxq, bd, len, pad);
if (unlikely(!skb))
return NULL;
bd->page_offset += rxq->rx_buf_seg_size;
if (bd->page_offset == PAGE_SIZE) {
@@ -812,6 +815,8 @@ qede_rx_build_skb(struct qede_dev *edev,
}
skb = qede_build_skb(rxq, bd, len, pad);
if (unlikely(!skb))
return NULL;
if (unlikely(qede_realloc_rx_buffer(rxq, bd))) {
/* Incr page ref count to reuse on allocation failure so