NULL Pointer Dereference Affecting perf package, versions *

Note: Versions mentioned in the description apply only to the upstream perf package and not the perf package as distributed by RHEL. See How to fix? for RHEL:8 relevant fixed versions and status.

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

net/mlx5: Fix bridge mode operations when there are no VFs

Currently, trying to set the bridge mode attribute when numvfs=0 leads to a crash:

bridge link set dev eth2 hwmode vepa

[ 168.967392] BUG: kernel NULL pointer dereference, address: 0000000000000030 [...] [ 168.969989] RIP: 0010:mlx5_add_flow_rules+0x1f/0x300 [mlx5_core] [...] [ 168.976037] Call Trace: [ 168.976188] <TASK> [ 168.978620] _mlx5_eswitch_set_vepa_locked+0x113/0x230 [mlx5_core] [ 168.979074] mlx5_eswitch_set_vepa+0x7f/0xa0 [mlx5_core] [ 168.979471] rtnl_bridge_setlink+0xe9/0x1f0 [ 168.979714] rtnetlink_rcv_msg+0x159/0x400 [ 168.980451] netlink_rcv_skb+0x54/0x100 [ 168.980675] netlink_unicast+0x241/0x360 [ 168.980918] netlink_sendmsg+0x1f6/0x430 [ 168.981162] ____sys_sendmsg+0x3bb/0x3f0 [ 168.982155] ___sys_sendmsg+0x88/0xd0 [ 168.985036] __sys_sendmsg+0x59/0xa0 [ 168.985477] do_syscall_64+0x79/0x150 [ 168.987273] entry_SYSCALL_64_after_hwframe+0x76/0x7e [ 168.987773] RIP: 0033:0x7f8f7950f917

(esw->fdb_table.legacy.vepa_fdb is null)

The bridge mode is only relevant when there are multiple functions per port. Therefore, prevent setting and getting this setting when there are no VFs.

Note that after this change, there are no settings to change on the PF interface using bridge link when there are no VFs, so the interface no longer appears in the bridge link output.

• https://access.redhat.com/security/cve/CVE-2024-46857
• https://git.kernel.org/stable/c/505ae01f75f839b54329164bbfecf24cc1361b31
• https://git.kernel.org/stable/c/52c4beb79e095e0631b5cac46ed48a2aefe51985
• https://git.kernel.org/stable/c/65feee671e37f3b6eda0b6af28f204b5bcf7fa50
• https://git.kernel.org/stable/c/b1d305abef4640af1b4f1b4774d513cd81b10cfc