kernel/linux.git/net/core/rtnetlink.c, branch linux-7.0.y

net: rtnetlink: zero ifla_vf_broadcast to avoid stack infoleak in rtnl_fill_vfinfo

2026-05-14T13:31:07+00:00

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 Link: https://patch.msgid.link/3c506e8f936e52b57620269b55c348af05d413a2.1777557228.git.kai.aizen.dev@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

rtnetlink: add missing netlink_ns_capable() check for peer netns

2026-04-03T22:07:18+00:00

rtnl_newlink() lacks a CAP_NET_ADMIN capability check on the peer network namespace when creating paired devices (veth, vxcan, netkit). This allows an unprivileged user with a user namespace to create interfaces in arbitrary network namespaces, including init_net. Add a netlink_ns_capable() check for CAP_NET_ADMIN in the peer namespace before allowing device creation to proceed. Fixes: 81adee47dfb6 ("net: Support specifying the network namespace upon device creation.") Signed-off-by: Nikolaos Gkarlis Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20260402181432.4126920-1-nickgarlis@gmail.com Signed-off-by: Jakub Kicinski

rtnetlink: fix leak of SRCU struct in rtnl_link_register

2026-03-25T03:56:02+00:00

Commit 6b57ff21a310 ("rtnetlink: Protect link_ops by mutex.") swapped the EEXIST check with the init_srcu_struct, but didn't add cleanup of the SRCU struct we just allocated in case of error. Fixes: 6b57ff21a310 ("rtnetlink: Protect link_ops by mutex.") Signed-off-by: Sabrina Dubroca Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/e77fe499f9a58c547b33b5212b3596dad417cec6.1774025341.git.sd@queasysnail.net Signed-off-by: Jakub Kicinski

rtnetlink: count IFLA_INFO_SLAVE_KIND in if_nlmsg_size

2026-03-21T02:05:12+00:00

rtnl_link_get_slave_info_data_size counts IFLA_INFO_SLAVE_DATA, but rtnl_link_slave_info_fill adds both IFLA_INFO_SLAVE_DATA and IFLA_INFO_SLAVE_KIND. Fixes: ba7d49b1f0f8 ("rtnetlink: provide api for getting and setting slave info") Reviewed-by: Jiri Pirko Signed-off-by: Sabrina Dubroca Link: https://patch.msgid.link/049843b532e23cde7ddba263c0bbe35ba6f0d26d.1773919462.git.sd@queasysnail.net Signed-off-by: Jakub Kicinski

rtnetlink: count IFLA_PARENT_DEV_{NAME,BUS_NAME} in if_nlmsg_size

2026-03-21T02:05:11+00:00

Commit 00e77ed8e64d ("rtnetlink: add IFLA_PARENT_[DEV|DEV_BUS]_NAME") added those attributes to rtnl_fill_ifinfo, but forgot to extend if_nlmsg_size. Fixes: 00e77ed8e64d ("rtnetlink: add IFLA_PARENT_[DEV|DEV_BUS]_NAME") Signed-off-by: Sabrina Dubroca Link: https://patch.msgid.link/0b849da95562af45487080528d60f578636aba5c.1773919462.git.sd@queasysnail.net Signed-off-by: Jakub Kicinski

Convert 'alloc_obj' family to use the new default GFP_KERNEL argument

2026-02-22T01:09:51+00:00

This was done entirely with mindless brute force, using git grep -l '\

treewide: Replace kmalloc with kmalloc_obj for non-scalar types

2026-02-21T09:02:28+00:00

This is the result of running the Coccinelle script from scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to avoid scalar types (which need careful case-by-case checking), and instead replace kmalloc-family calls that allocate struct or union object instances: Single allocations: kmalloc(sizeof(TYPE), ...) are replaced with: kmalloc_obj(TYPE, ...) Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...) are replaced with: kmalloc_objs(TYPE, COUNT, ...) Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...) are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...) (where TYPE may also be *VAR) The resulting allocations no longer return "void *", instead returning "TYPE *". Signed-off-by: Kees Cook

rtnetlink: honor RTEXT_FILTER_SKIP_STATS in IFLA_STATS

2025-11-05T00:07:37+00:00

Gathering interface statistics can be a relatively expensive operation on certain systems as it requires iterating over all the cpus. RTEXT_FILTER_SKIP_STATS was first introduced [1] to skip AF_INET6 statistics from interface dumps and it was then extended [2] to also exclude IFLA_VF_INFO. The semantics of the flag does not seem to be limited to AF_INET or VF statistics and having a way to query the interface status (e.g: carrier, address) without retrieving its statistics seems reasonable. So this patch extends the use RTEXT_FILTER_SKIP_STATS to also affect IFLA_STATS. [1] https://lore.kernel.org/all/20150911204848.GC9687@oracle.com/ [2] https://lore.kernel.org/all/20230611105108.122586-1-gal@nvidia.com/ Signed-off-by: Adrian Moreno Reviewed-by: Toke Høiland-Jørgensen Reviewed-by: Eric Dumazet Reviewed-by: Nicolas Dichtel Link: https://patch.msgid.link/20251103154006.1189707-1-amorenoz@redhat.com Signed-off-by: Jakub Kicinski

rtnetlink: Allow deleting FDB entries in user namespace

2025-10-16T23:09:56+00:00

Creating FDB entries is possible from a non-initial user namespace when having CAP_NET_ADMIN, yet, when deleting FDB entries, processes receive an EPERM because the capability is always checked against the initial user namespace. This restricts the FDB management from unprivileged containers. Drop the netlink_capable check in rtnl_fdb_del as it was originally dropped in c5c351088ae7 and reintroduced in 1690be63a27b without intention. This patch was tested using a container on GyroidOS, where it was possible to delete FDB entries from an unprivileged user namespace and private network namespace. Fixes: 1690be63a27b ("bridge: Add vlan support to static neighbors") Reviewed-by: Michael Weiß Tested-by: Harshal Gohel Signed-off-by: Johannes Wiesböck Reviewed-by: Ido Schimmel Reviewed-by: Nikolay Aleksandrov Link: https://patch.msgid.link/20251015201548.319871-1-johannes.wiesboeck@aisec.fraunhofer.de Signed-off-by: Jakub Kicinski

net: rtnetlink: fix typo in rtnl_unregister_all() comment

2025-09-30T01:31:08+00:00

Corrected "rtnl_unregster()" -> "rtnl_unregister()" in the documentation comment of "rtnl_unregister_all()" Signed-off-by: Alok Tiwari Reviewed-by: Simon Horman Link: https://patch.msgid.link/20250929085418.49200-1-alok.a.tiwari@oracle.com Signed-off-by: Jakub Kicinski