linux-stable.git/net/core, branch v6.6.141 Linux kernel stable tree net: skbuff: propagate shared-frag marker through frag-transfer helpers 2026-05-23T11:03:36+00:00 Hyunwoo Kim imv4bel@gmail.com 2026-05-15T22:28:53+00:00 989214c66884d70716d83dc1d0bf5e16287bf349 commit 48f6a5356a33dd78e7144ae1faef95ffc990aae0 upstream. Two frag-transfer helpers (__pskb_copy_fclone() and skb_shift()) fail to propagate the SKBFL_SHARED_FRAG bit in skb_shinfo()->flags when moving frags from source to destination. __pskb_copy_fclone() defers the rest of the shinfo metadata to skb_copy_header() after copying frag descriptors, but that helper only carries over gso_{size,segs, type} and never touches skb_shinfo()->flags; skb_shift() moves frag descriptors directly and leaves flags untouched. As a result, the destination skb keeps a reference to the same externally-owned or page-cache-backed pages while reporting skb_has_shared_frag() as false. The mismatch is harmful in any in-place writer that uses skb_has_shared_frag() to decide whether shared pages must be detoured through skb_cow_data(). ESP input is one such writer (esp4.c, esp6.c), and a single nft 'dup to <local>' rule -- or any other nf_dup_ipv4() / xt_TEE caller -- is enough to land a pskb_copy()'d skb in esp_input() with the marker stripped, letting an unprivileged user write into the page cache of a root-owned read-only file via authencesn-ESN stray writes. Set SKBFL_SHARED_FRAG on the destination whenever frag descriptors were actually moved from the source. skb_copy() and skb_copy_expand() share skb_copy_header() too but linearize all paged data into freshly allocated head storage and emerge with nr_frags == 0, so skb_has_shared_frag() returns false on its own; they need no change. The same omission exists in skb_gro_receive() and skb_gro_receive_list(). The former moves the incoming skb's frag descriptors into the accumulator's last sub-skb via two paths (a direct frag-move loop and the head_frag + memcpy path); the latter chains the incoming skb whole onto p's frag_list. Downstream skb_segment() reads only skb_shinfo(p)->flags, and skb_segment_list() reuses each sub-skb's shinfo as the nskb -- both p and lp must carry the marker. The same omission also exists in tcp_clone_payload(), which builds an MTU probe skb by moving frag descriptors from skbs on sk_write_queue into a freshly allocated nskb. The helper falls into the same family and warrants the same fix for consistency; no TCP TX-side in-place writer is currently known to reach a user page through this gap, but a future consumer depending on the marker would regress silently. The same omission exists in skb_segment(): the per-iteration flag merge takes only head_skb's flag, and the inner switch that rebinds frag_skb to list_skb on head_skb-frags exhaustion does not fold the new frag_skb's flag into nskb. Fold frag_skb's flag at both sites so segments drawing frags from frag_list members carry the marker. Fixes: cef401de7be8 ("net: fix possible wrong checksum generation") Fixes: f4c50a4034e6 ("xfrm: esp: avoid in-place decrypt on shared skb frags") Suggested-by: Sabrina Dubroca <sd@queasysnail.net> Suggested-by: Sultan Alsawaf <sultan@kerneltoast.com> Suggested-by: Ben Hutchings <ben@decadent.org.uk> Suggested-by: Lin Ma <malin89@huawei.com> Suggested-by: Jingguo Tan <tanjingguo@huawei.com> Suggested-by: Aaron Esau <aaron1esau@gmail.com> Cc: stable@vger.kernel.org Signed-off-by: Hyunwoo Kim <imv4bel@gmail.com> Tested-by: Rajat Gupta <rajat.gupta@oss.qualcomm.com> Link: https://patch.msgid.link/ageeJfJHwgzmKXbh@v4bel Signed-off-by: Paolo Abeni <pabeni@redhat.com> [bwh: Backported to 6.6: skb_gro_receive_list() is in net/ipv4/udp_offload.c here] Signed-off-by: Ben Hutchings <benh@debian.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 48f6a5356a33dd78e7144ae1faef95ffc990aae0 upstream.

Two frag-transfer helpers (__pskb_copy_fclone() and skb_shift()) fail
to propagate the SKBFL_SHARED_FRAG bit in skb_shinfo()->flags when
moving frags from source to destination.  __pskb_copy_fclone() defers
the rest of the shinfo metadata to skb_copy_header() after copying
frag descriptors, but that helper only carries over gso_{size,segs,
type} and never touches skb_shinfo()->flags; skb_shift() moves frag
descriptors directly and leaves flags untouched.  As a result, the
destination skb keeps a reference to the same externally-owned or
page-cache-backed pages while reporting skb_has_shared_frag() as
false.

The mismatch is harmful in any in-place writer that uses
skb_has_shared_frag() to decide whether shared pages must be detoured
through skb_cow_data().  ESP input is one such writer (esp4.c,
esp6.c), and a single nft 'dup to <local>' rule -- or any other
nf_dup_ipv4() / xt_TEE caller -- is enough to land a pskb_copy()'d
skb in esp_input() with the marker stripped, letting an unprivileged
user write into the page cache of a root-owned read-only file via
authencesn-ESN stray writes.

Set SKBFL_SHARED_FRAG on the destination whenever frag descriptors
were actually moved from the source.  skb_copy() and skb_copy_expand()
share skb_copy_header() too but linearize all paged data into freshly
allocated head storage and emerge with nr_frags == 0, so
skb_has_shared_frag() returns false on its own; they need no change.

The same omission exists in skb_gro_receive() and skb_gro_receive_list().
The former moves the incoming skb's frag descriptors into the
accumulator's last sub-skb via two paths (a direct frag-move loop and
the head_frag + memcpy path); the latter chains the incoming skb whole
onto p's frag_list.  Downstream skb_segment() reads only
skb_shinfo(p)->flags, and skb_segment_list() reuses each sub-skb's
shinfo as the nskb -- both p and lp must carry the marker.

The same omission also exists in tcp_clone_payload(), which builds an
MTU probe skb by moving frag descriptors from skbs on sk_write_queue
into a freshly allocated nskb.  The helper falls into the same family
and warrants the same fix for consistency; no TCP TX-side in-place
writer is currently known to reach a user page through this gap, but
a future consumer depending on the marker would regress silently.

The same omission exists in skb_segment(): the per-iteration flag
merge takes only head_skb's flag, and the inner switch that rebinds
frag_skb to list_skb on head_skb-frags exhaustion does not fold the
new frag_skb's flag into nskb.  Fold frag_skb's flag at both sites
so segments drawing frags from frag_list members carry the marker.

Fixes: cef401de7be8 ("net: fix possible wrong checksum generation")
Fixes: f4c50a4034e6 ("xfrm: esp: avoid in-place decrypt on shared skb frags")
Suggested-by: Sabrina Dubroca <sd@queasysnail.net>
Suggested-by: Sultan Alsawaf <sultan@kerneltoast.com>
Suggested-by: Ben Hutchings <ben@decadent.org.uk>
Suggested-by: Lin Ma <malin89@huawei.com>
Suggested-by: Jingguo Tan <tanjingguo@huawei.com>
Suggested-by: Aaron Esau <aaron1esau@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Hyunwoo Kim <imv4bel@gmail.com>
Tested-by: Rajat Gupta <rajat.gupta@oss.qualcomm.com>
Link: https://patch.msgid.link/ageeJfJHwgzmKXbh@v4bel
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
[bwh: Backported to 6.6: skb_gro_receive_list() is in
 net/ipv4/udp_offload.c here]
Signed-off-by: Ben Hutchings <benh@debian.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
net: skbuff: preserve shared-frag marker during coalescing 2026-05-23T11:03:35+00:00 William Bowling vakzz@zellic.io 2026-05-13T04:16:35+00:00 78bf6b6bb19541d19fbda6242e7cfe2c682763c0 commit f84eca5817390257cef78013d0112481c503b4a3 upstream. skb_try_coalesce() can attach paged frags from @from to @to. If @from has SKBFL_SHARED_FRAG set, the resulting @to skb can contain the same externally-owned or page-cache-backed frags, but the shared-frag marker is currently lost. That breaks the invariant relied on by later in-place writers. In particular, ESP input checks skb_has_shared_frag() before deciding whether an uncloned nonlinear skb can skip skb_cow_data(). If TCP receive coalescing has moved shared frags into an unmarked skb, ESP can see skb_has_shared_frag() as false and decrypt in place over page-cache backed frags. Propagate SKBFL_SHARED_FRAG when skb_try_coalesce() transfers paged frags. The tailroom copy path does not need the marker because it copies bytes into @to's linear data rather than transferring frag descriptors. Fixes: cef401de7be8 ("net: fix possible wrong checksum generation") Fixes: f4c50a4034e6 ("xfrm: esp: avoid in-place decrypt on shared skb frags") Signed-off-by: William Bowling <vakzz@zellic.io> Reviewed-by: Eric Dumazet <edumazet@google.com> Tested-by: Jiayuan Chen <jiayuan.chen@linux.dev> Link: https://patch.msgid.link/20260513041635.1289541-1-vakzz@zellic.io Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit f84eca5817390257cef78013d0112481c503b4a3 upstream.

skb_try_coalesce() can attach paged frags from @from to @to.  If @from
has SKBFL_SHARED_FRAG set, the resulting @to skb can contain the same
externally-owned or page-cache-backed frags, but the shared-frag marker
is currently lost.

That breaks the invariant relied on by later in-place writers.  In
particular, ESP input checks skb_has_shared_frag() before deciding
whether an uncloned nonlinear skb can skip skb_cow_data().  If TCP
receive coalescing has moved shared frags into an unmarked skb, ESP can
see skb_has_shared_frag() as false and decrypt in place over page-cache
backed frags.

Propagate SKBFL_SHARED_FRAG when skb_try_coalesce() transfers paged
frags.  The tailroom copy path does not need the marker because it copies
bytes into @to's linear data rather than transferring frag descriptors.

Fixes: cef401de7be8 ("net: fix possible wrong checksum generation")
Fixes: f4c50a4034e6 ("xfrm: esp: avoid in-place decrypt on shared skb frags")
Signed-off-by: William Bowling <vakzz@zellic.io>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Tested-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Link: https://patch.msgid.link/20260513041635.1289541-1-vakzz@zellic.io
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
neigh: let neigh_xmit take skb ownership 2026-05-23T11:03:28+00:00 Florian Westphal fw@strlen.de 2026-04-24T14:58:38+00:00 9247d59ca15bf60a57dca08103f055d8a4340877 [ Upstream commit 4438113be604ee67a7bf4f81da6e1cca41332ce4 ] neigh_xmit always releases the skb, except when no neighbour table is found. But even the first added user of neigh_xmit (mpls) relied on neigh_xmit to release the skb (or queue it for tx). sashiko reported: If neigh_xmit() is called with an uninitialized neighbor table (for example, NEIGH_ND_TABLE when IPv6 is disabled), it returns -EAFNOSUPPORT and bypasses its internal out_kfree_skb error path. Because the return value of neigh_xmit() is ignored here, does this leak the SKB? Assume full ownership and remove the last code path that doesn't xmit or free skb. Fixes: 4fd3d7d9e868 ("neigh: Add helper function neigh_xmit") Signed-off-by: Florian Westphal <fw@strlen.de> Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com> Reviewed-by: Ido Schimmel <idosch@nvidia.com> Link: https://patch.msgid.link/20260424145843.74055-1-fw@strlen.de Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 4438113be604ee67a7bf4f81da6e1cca41332ce4 ]

neigh_xmit always releases the skb, except when no neighbour table is
found. But even the first added user of neigh_xmit (mpls) relied on
neigh_xmit to release the skb (or queue it for tx).

sashiko reported:
 If neigh_xmit() is called with an uninitialized neighbor table (for
 example, NEIGH_ND_TABLE when IPv6 is disabled), it returns -EAFNOSUPPORT
 and bypasses its internal out_kfree_skb error path.  Because the return
 value of neigh_xmit() is ignored here, does this leak the SKB?

Assume full ownership and remove the last code path that doesn't
xmit or free skb.

Fixes: 4fd3d7d9e868 ("neigh: Add helper function neigh_xmit")
Signed-off-by: Florian Westphal <fw@strlen.de>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20260424145843.74055-1-fw@strlen.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
neighbour: add RCU protection to neigh_tables[] 2026-05-23T11:03:28+00:00 Eric Dumazet edumazet@google.com 2024-04-18T09:51:04+00:00 dbe42409bfeb9928b4b88c9098dd6fa487cfa20b [ Upstream commit f8f2eb9de69a1119117d198547c13d7a1123a5a9 ] In order to remove RTNL protection from neightbl_dump_info() and neigh_dump_info() later, we need to add RCU protection to neigh_tables[]. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Stable-dep-of: 4438113be604 ("neigh: let neigh_xmit take skb ownership") Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit f8f2eb9de69a1119117d198547c13d7a1123a5a9 ]

In order to remove RTNL protection from neightbl_dump_info()
and neigh_dump_info() later, we need to add
RCU protection to neigh_tables[].

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Stable-dep-of: 4438113be604 ("neigh: let neigh_xmit take skb ownership")
Signed-off-by: Sasha Levin <sashal@kernel.org>
bpf: Fix precedence bug in convert_bpf_ld_abs alignment check 2026-05-23T11:03:19+00:00 Daniel Borkmann daniel@iogearbox.net 2026-04-16T12:27:19+00:00 2f954f8a04b749d81afec3945a00fd65442ccf8e [ Upstream commit e5f635edd393aeaa7cad9e42831d397e6e2e1eed ] Fix an operator precedence issue in convert_bpf_ld_abs() where the expression offset + ip_align % size evaluates as offset + (ip_align % size) due to % having higher precedence than +. That latter evaluation does not make any sense. The intended check is (offset + ip_align) % size == 0 to verify that the packet load offset is properly aligned for direct access. With NET_IP_ALIGN == 2, the bug causes the inline fast-path for direct packet loads to almost never be taken on !CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS platforms. This forces nearly all cBPF BPF_LD_ABS packet loads through the bpf_skb_load_helper slow path on the affected archs. Fixes: e0cea7ce988c ("bpf: implement ld_abs/ld_ind in native bpf") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/r/20260416122719.661033-1-daniel@iogearbox.net Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit e5f635edd393aeaa7cad9e42831d397e6e2e1eed ]

Fix an operator precedence issue in convert_bpf_ld_abs() where the
expression offset + ip_align % size evaluates as offset + (ip_align % size)
due to % having higher precedence than +. That latter evaluation does
not make any sense. The intended check is (offset + ip_align) % size == 0
to verify that the packet load offset is properly aligned for direct
access.

With NET_IP_ALIGN == 2, the bug causes the inline fast-path for direct
packet loads to almost never be taken on !CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
platforms. This forces nearly all cBPF BPF_LD_ABS packet loads through
the bpf_skb_load_helper slow path on the affected archs.

Fixes: e0cea7ce988c ("bpf: implement ld_abs/ld_ind in native bpf")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20260416122719.661033-1-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
net, bpf: fix null-ptr-deref in xdp_master_redirect() for down master 2026-05-23T11:03:10+00:00 Jiayuan Chen jiayuan.chen@linux.dev 2026-04-11T00:55:19+00:00 866d3d9b87751b1944168fd82615505e0c0fd6cf [ Upstream commit 1921f91298d1388a0bb9db8f83800c998b649cb3 ] syzkaller reported a kernel panic in bond_rr_gen_slave_id() reached via xdp_master_redirect(). Full decoded trace: https://syzkaller.appspot.com/bug?extid=80e046b8da2820b6ba73 bond_rr_gen_slave_id() dereferences bond->rr_tx_counter, a per-CPU counter that bonding only allocates in bond_open() when the mode is round-robin. If the bond device was never brought up, rr_tx_counter stays NULL. The XDP redirect path can still reach that code on a bond that was never opened: bpf_master_redirect_enabled_key is a global static key, so as soon as any bond device has native XDP attached, the XDP_TX -> xdp_master_redirect() interception is enabled for every slave system-wide. The path xdp_master_redirect() -> bond_xdp_get_xmit_slave() -> bond_xdp_xmit_roundrobin_slave_get() -> bond_rr_gen_slave_id() then runs against a bond that has no rr_tx_counter and crashes. Fix this in the generic xdp_master_redirect() by refusing to call into the master's ->ndo_xdp_get_xmit_slave() when the master device is not up. IFF_UP is only set after ->ndo_open() has successfully returned, so this reliably excludes masters whose XDP state has not been fully initialized. Drop the frame with XDP_ABORTED so the exception is visible via trace_xdp_exception() rather than silently falling through. This is not specific to bonding: any current or future master that defers XDP state allocation to ->ndo_open() is protected. Fixes: 879af96ffd72 ("net, core: Add support for XDP redirection to slave device") Reported-by: syzbot+80e046b8da2820b6ba73@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/698f84c6.a70a0220.2c38d7.00cc.GAE@google.com/T/ Suggested-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev> Link: https://patch.msgid.link/20260411005524.201200-2-jiayuan.chen@linux.dev Signed-off-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 1921f91298d1388a0bb9db8f83800c998b649cb3 ]

syzkaller reported a kernel panic in bond_rr_gen_slave_id() reached via
xdp_master_redirect(). Full decoded trace:

  https://syzkaller.appspot.com/bug?extid=80e046b8da2820b6ba73

bond_rr_gen_slave_id() dereferences bond->rr_tx_counter, a per-CPU
counter that bonding only allocates in bond_open() when the mode is
round-robin. If the bond device was never brought up, rr_tx_counter
stays NULL.

The XDP redirect path can still reach that code on a bond that was
never opened: bpf_master_redirect_enabled_key is a global static key,
so as soon as any bond device has native XDP attached, the
XDP_TX -> xdp_master_redirect() interception is enabled for every
slave system-wide. The path xdp_master_redirect() ->
bond_xdp_get_xmit_slave() -> bond_xdp_xmit_roundrobin_slave_get() ->
bond_rr_gen_slave_id() then runs against a bond that has no
rr_tx_counter and crashes.

Fix this in the generic xdp_master_redirect() by refusing to call into
the master's ->ndo_xdp_get_xmit_slave() when the master device is not
up. IFF_UP is only set after ->ndo_open() has successfully returned,
so this reliably excludes masters whose XDP state has not been fully
initialized. Drop the frame with XDP_ABORTED so the exception is
visible via trace_xdp_exception() rather than silently falling through.
This is not specific to bonding: any current or future master that
defers XDP state allocation to ->ndo_open() is protected.

Fixes: 879af96ffd72 ("net, core: Add support for XDP redirection to slave device")
Reported-by: syzbot+80e046b8da2820b6ba73@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/698f84c6.a70a0220.2c38d7.00cc.GAE@google.com/T/
Suggested-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Link: https://patch.msgid.link/20260411005524.201200-2-jiayuan.chen@linux.dev
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
net: rtnetlink: zero ifla_vf_broadcast to avoid stack infoleak in rtnl_fill_vfinfo 2026-05-17T15:13:38+00:00 Kai Zen kai.aizen.dev@gmail.com 2026-04-30T15:26:48+00:00 0653c0516234c8258975d268a749115fc0f0ff00 commit 4b9e327991815e128ad3af75c3a04630a63ce3e0 upstream. rtnl_fill_vfinfo() declares struct ifla_vf_broadcast on the stack without initialisation: struct ifla_vf_broadcast vf_broadcast; The struct contains a single fixed 32-byte field: /* include/uapi/linux/if_link.h */ struct ifla_vf_broadcast { __u8 broadcast[32]; }; The function then copies dev->broadcast into it using dev->addr_len as the length: memcpy(vf_broadcast.broadcast, dev->broadcast, dev->addr_len); On Ethernet devices (the overwhelming majority of SR-IOV NICs) dev->addr_len is 6, so only the first 6 bytes of broadcast[] are written. The remaining 26 bytes retain whatever was previously on the kernel stack. The full struct is then handed to userspace via: nla_put(skb, IFLA_VF_BROADCAST, sizeof(vf_broadcast), &vf_broadcast) leaking up to 26 bytes of uninitialised kernel stack per VF per RTM_GETLINK request, repeatable. The other vf_* structs in the same function are explicitly zeroed for exactly this reason - see the memset() calls for ivi, vf_vlan_info, node_guid and port_guid a few lines above. vf_broadcast was simply missed when it was added. Reachability: any unprivileged local process can open AF_NETLINK / NETLINK_ROUTE without capabilities and send RTM_GETLINK with an IFLA_EXT_MASK attribute carrying RTEXT_FILTER_VF. The kernel walks each VF and emits IFLA_VF_BROADCAST, leaking 26 bytes of stack per VF per request. Stack residue at this call site can include return addresses and transient sensitive data; KASAN with stack instrumentation, or KMSAN, will flag the nla_put() when reproduced. Zero the on-stack struct before the partial memcpy, matching the existing pattern used for the other vf_* structs in the same function. Fixes: 75345f888f70 ("ipoib: show VF broadcast address") Cc: stable@vger.kernel.org Signed-off-by: Kai Zen <kai.aizen.dev@gmail.com> Link: https://patch.msgid.link/3c506e8f936e52b57620269b55c348af05d413a2.1777557228.git.kai.aizen.dev@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 4b9e327991815e128ad3af75c3a04630a63ce3e0 upstream.

rtnl_fill_vfinfo() declares struct ifla_vf_broadcast on the stack
without initialisation:

	struct ifla_vf_broadcast vf_broadcast;

The struct contains a single fixed 32-byte field:

	/* include/uapi/linux/if_link.h */
	struct ifla_vf_broadcast {
		__u8 broadcast[32];
	};

The function then copies dev->broadcast into it using dev->addr_len
as the length:

	memcpy(vf_broadcast.broadcast, dev->broadcast, dev->addr_len);

On Ethernet devices (the overwhelming majority of SR-IOV NICs)
dev->addr_len is 6, so only the first 6 bytes of broadcast[] are
written. The remaining 26 bytes retain whatever was previously on
the kernel stack. The full struct is then handed to userspace via:

	nla_put(skb, IFLA_VF_BROADCAST,
		sizeof(vf_broadcast), &vf_broadcast)

leaking up to 26 bytes of uninitialised kernel stack per VF per
RTM_GETLINK request, repeatable.

The other vf_* structs in the same function are explicitly zeroed
for exactly this reason - see the memset() calls for ivi,
vf_vlan_info, node_guid and port_guid a few lines above.
vf_broadcast was simply missed when it was added.

Reachability: any unprivileged local process can open AF_NETLINK /
NETLINK_ROUTE without capabilities and send RTM_GETLINK with an
IFLA_EXT_MASK attribute carrying RTEXT_FILTER_VF. The kernel walks
each VF and emits IFLA_VF_BROADCAST, leaking 26 bytes of stack per
VF per request. Stack residue at this call site can include return
addresses and transient sensitive data; KASAN with stack
instrumentation, or KMSAN, will flag the nla_put() when reproduced.

Zero the on-stack struct before the partial memcpy, matching the
existing pattern used for the other vf_* structs in the same
function.

Fixes: 75345f888f70 ("ipoib: show VF broadcast address")
Cc: stable@vger.kernel.org
Signed-off-by: Kai Zen <kai.aizen.dev@gmail.com>
Link: https://patch.msgid.link/3c506e8f936e52b57620269b55c348af05d413a2.1777557228.git.kai.aizen.dev@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
flow_dissector: do not dissect PPPoE PFC frames 2026-05-17T15:13:35+00:00 Qingfang Deng qingfang.deng@linux.dev 2026-04-15T02:24:50+00:00 db104b0d8a7856397c0469d83a4289adf7c54863 [ Upstream commit d6c19b31a3c1d519fabdcf0aa239e6b6109b9473 ] RFC 2516 Section 7 states that Protocol Field Compression (PFC) is NOT RECOMMENDED for PPPoE. In practice, pppd does not support negotiating PFC for PPPoE sessions, and the flow dissector driver has assumed an uncompressed frame until the blamed commit. During the review process of that commit [1], support for PFC is suggested. However, having a compressed (1-byte) protocol field means the subsequent PPP payload is shifted by one byte, causing 4-byte misalignment for the network header and an unaligned access exception on some architectures. The exception can be reproduced by sending a PPPoE PFC frame to an ethernet interface of a MIPS board, with RPS enabled, even if no PPPoE session is active on that interface: $ 0 : 00000000 80c40000 00000000 85144817 $ 4 : 00000008 00000100 80a75758 81dc9bb8 $ 8 : 00000010 8087ae2c 0000003d 00000000 $12 : 000000e0 00000039 00000000 00000000 $16 : 85043240 80a75758 81dc9bb8 00006488 $20 : 0000002f 00000007 85144810 80a70000 $24 : 81d1bda0 00000000 $28 : 81dc8000 81dc9aa8 00000000 805ead08 Hi : 00009d51 Lo : 2163358a epc : 805e91f0 __skb_flow_dissect+0x1b0/0x1b50 ra : 805ead08 __skb_get_hash_net+0x74/0x12c Status: 11000403 KERNEL EXL IE Cause : 40800010 (ExcCode 04) BadVA : 85144817 PrId : 0001992f (MIPS 1004Kc) Call Trace: [<805e91f0>] __skb_flow_dissect+0x1b0/0x1b50 [<805ead08>] __skb_get_hash_net+0x74/0x12c [<805ef330>] get_rps_cpu+0x1b8/0x3fc [<805fca70>] netif_receive_skb_list_internal+0x324/0x364 [<805fd120>] napi_complete_done+0x68/0x2a4 [<8058de5c>] mtk_napi_rx+0x228/0xfec [<805fd398>] __napi_poll+0x3c/0x1c4 [<805fd754>] napi_threaded_poll_loop+0x234/0x29c [<805fd848>] napi_threaded_poll+0x8c/0xb0 [<80053544>] kthread+0x104/0x12c [<80002bd8>] ret_from_kernel_thread+0x14/0x1c Code: 02d51821 1060045b 00000000 <8c640000> 3084000f 2c820005 144001a2 00042080 8e220000 To reduce the attack surface and maintain performance, do not process PPPoE PFC frames. [1] https://lore.kernel.org/r/20220630231016.GA392@debian.home Fixes: 46126db9c861 ("flow_dissector: Add PPPoE dissectors") Signed-off-by: Qingfang Deng <qingfang.deng@linux.dev> Link: https://patch.msgid.link/20260415022456.141758-1-qingfang.deng@linux.dev Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit d6c19b31a3c1d519fabdcf0aa239e6b6109b9473 ]

RFC 2516 Section 7 states that Protocol Field Compression (PFC) is NOT
RECOMMENDED for PPPoE. In practice, pppd does not support negotiating
PFC for PPPoE sessions, and the flow dissector driver has assumed an
uncompressed frame until the blamed commit.

During the review process of that commit [1], support for PFC is
suggested. However, having a compressed (1-byte) protocol field means
the subsequent PPP payload is shifted by one byte, causing 4-byte
misalignment for the network header and an unaligned access exception
on some architectures.

The exception can be reproduced by sending a PPPoE PFC frame to an
ethernet interface of a MIPS board, with RPS enabled, even if no PPPoE
session is active on that interface:

$ 0   : 00000000 80c40000 00000000 85144817
$ 4   : 00000008 00000100 80a75758 81dc9bb8
$ 8   : 00000010 8087ae2c 0000003d 00000000
$12   : 000000e0 00000039 00000000 00000000
$16   : 85043240 80a75758 81dc9bb8 00006488
$20   : 0000002f 00000007 85144810 80a70000
$24   : 81d1bda0 00000000
$28   : 81dc8000 81dc9aa8 00000000 805ead08
Hi    : 00009d51
Lo    : 2163358a
epc   : 805e91f0 __skb_flow_dissect+0x1b0/0x1b50
ra    : 805ead08 __skb_get_hash_net+0x74/0x12c
Status: 11000403        KERNEL EXL IE
Cause : 40800010 (ExcCode 04)
BadVA : 85144817
PrId  : 0001992f (MIPS 1004Kc)
Call Trace:
[<805e91f0>] __skb_flow_dissect+0x1b0/0x1b50
[<805ead08>] __skb_get_hash_net+0x74/0x12c
[<805ef330>] get_rps_cpu+0x1b8/0x3fc
[<805fca70>] netif_receive_skb_list_internal+0x324/0x364
[<805fd120>] napi_complete_done+0x68/0x2a4
[<8058de5c>] mtk_napi_rx+0x228/0xfec
[<805fd398>] __napi_poll+0x3c/0x1c4
[<805fd754>] napi_threaded_poll_loop+0x234/0x29c
[<805fd848>] napi_threaded_poll+0x8c/0xb0
[<80053544>] kthread+0x104/0x12c
[<80002bd8>] ret_from_kernel_thread+0x14/0x1c

Code: 02d51821  1060045b  00000000 <8c640000> 3084000f  2c820005  144001a2  00042080  8e220000

To reduce the attack surface and maintain performance, do not process
PPPoE PFC frames.

[1] https://lore.kernel.org/r/20220630231016.GA392@debian.home
Fixes: 46126db9c861 ("flow_dissector: Add PPPoE dissectors")
Signed-off-by: Qingfang Deng <qingfang.deng@linux.dev>
Link: https://patch.msgid.link/20260415022456.141758-1-qingfang.deng@linux.dev
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
net: annotate data-races around sk->sk_{data_ready,write_space} 2026-04-27T13:23:34+00:00 Eric Dumazet edumazet@google.com 2026-04-22T02:16:26+00:00 7ad01905831c815520f1b0486336a03bb7420465 [ Upstream commit 2ef2b20cf4e04ac8a6ba68493f8780776ff84300 ] skmsg (and probably other layers) are changing these pointers while other cpus might read them concurrently. Add corresponding READ_ONCE()/WRITE_ONCE() annotations for UDP, TCP and AF_UNIX. Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface") Reported-by: syzbot+87f770387a9e5dc6b79b@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/699ee9fc.050a0220.1cd54b.0009.GAE@google.com/ Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: John Fastabend <john.fastabend@gmail.com> Cc: Jakub Sitnicki <jakub@cloudflare.com> Cc: Willem de Bruijn <willemdebruijn.kernel@gmail.com> Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com> Link: https://patch.msgid.link/20260225131547.1085509-1-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Leon Chen <leonchen.oss@139.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 2ef2b20cf4e04ac8a6ba68493f8780776ff84300 ]

skmsg (and probably other layers) are changing these pointers
while other cpus might read them concurrently.

Add corresponding READ_ONCE()/WRITE_ONCE() annotations
for UDP, TCP and AF_UNIX.

Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface")
Reported-by: syzbot+87f770387a9e5dc6b79b@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/699ee9fc.050a0220.1cd54b.0009.GAE@google.com/
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Jakub Sitnicki <jakub@cloudflare.com>
Cc: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20260225131547.1085509-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Leon Chen <leonchen.oss@139.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
net: add proper RCU protection to /proc/net/ptype 2026-04-27T13:23:32+00:00 Eric Dumazet edumazet@google.com 2026-04-14T12:11:18+00:00 002a73470b56848e4c81efeaaedd471e92d66d8d [ Upstream commit f613e8b4afea0cd17c7168e8b00e25bc8d33175d ] Yin Fengwei reported an RCU stall in ptype_seq_show() and provided a patch. Real issue is that ptype_seq_next() and ptype_seq_show() violate RCU rules. ptype_seq_show() runs under rcu_read_lock(), and reads pt->dev to get device name without any barrier. At the same time, concurrent writers can remove a packet_type structure (which is correctly freed after an RCU grace period) and clear pt->dev without an RCU grace period. Define ptype_iter_state to carry a dev pointer along seq_net_private: struct ptype_iter_state { struct seq_net_private p; struct net_device *dev; // added in this patch }; We need to record the device pointer in ptype_get_idx() and ptype_seq_next() so that ptype_seq_show() is safe against concurrent pt->dev changes. We also need to add full RCU protection in ptype_seq_next(). (Missing READ_ONCE() when reading list.next values) Many thanks to Dong Chenchen for providing a repro. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Fixes: 1d10f8a1f40b ("net-procfs: show net devices bound packet types") Fixes: c353e8983e0d ("net: introduce per netns packet chains") Reported-by: Yin Fengwei <fengwei_yin@linux.alibaba.com> Reported-by: Dong Chenchen <dongchenchen2@huawei.com> Closes: https://lore.kernel.org/netdev/CANn89iKRRKPnWjJmb-_3a=sq+9h6DvTQM4DBZHT5ZRGPMzQaiA@mail.gmail.com/T/#m7b80b9fc9b9267f90e0b7aad557595f686f9c50d Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Willem de Bruijn <willemb@google.com> Tested-by: Yin Fengwei <fengwei_yin@linux.alibaba.com> Link: https://patch.msgid.link/20260202205217.2881198-1-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> [ Some adjustments have been made. ] Signed-off-by: XiaoHua Wang <561399680@139.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit f613e8b4afea0cd17c7168e8b00e25bc8d33175d ]

Yin Fengwei reported an RCU stall in ptype_seq_show() and provided
a patch.

Real issue is that ptype_seq_next() and ptype_seq_show() violate
RCU rules.

ptype_seq_show() runs under rcu_read_lock(), and reads pt->dev
to get device name without any barrier.

At the same time, concurrent writers can remove a packet_type structure
(which is correctly freed after an RCU grace period) and clear pt->dev
without an RCU grace period.

Define ptype_iter_state to carry a dev pointer along seq_net_private:

struct ptype_iter_state {
	struct seq_net_private	p;
	struct net_device	*dev; // added in this patch
};

We need to record the device pointer in ptype_get_idx() and
ptype_seq_next() so that ptype_seq_show() is safe against
concurrent pt->dev changes.

We also need to add full RCU protection in ptype_seq_next().
(Missing READ_ONCE() when reading list.next values)

Many thanks to Dong Chenchen for providing a repro.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Fixes: 1d10f8a1f40b ("net-procfs: show net devices bound packet types")
Fixes: c353e8983e0d ("net: introduce per netns packet chains")
Reported-by: Yin Fengwei <fengwei_yin@linux.alibaba.com>
Reported-by: Dong Chenchen <dongchenchen2@huawei.com>
Closes: https://lore.kernel.org/netdev/CANn89iKRRKPnWjJmb-_3a=sq+9h6DvTQM4DBZHT5ZRGPMzQaiA@mail.gmail.com/T/#m7b80b9fc9b9267f90e0b7aad557595f686f9c50d

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Tested-by: Yin Fengwei <fengwei_yin@linux.alibaba.com>
Link: https://patch.msgid.link/20260202205217.2881198-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
[ Some adjustments have been made. ]
Signed-off-by: XiaoHua Wang <561399680@139.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>