2025-12-09 00:00:28
Linux
PUBLISHED
In the Linux kernel, the following vulnerability has been resolved:
bpf: Fix panic due to wrong pageattr of im->image
In the scenario where livepatch and kretfunc coexist, the pageattr of
im->image is rox after arch_prepare_bpf_trampoline in
bpf_trampoline_update, and then modify_fentry or register_fentry returns
-EAGAIN from bpf_tramp_ftrace_ops_func, the BPF_TRAMP_F_ORIG_STACK flag
will be configured, and arch_prepare_bpf_trampoline will be re-executed.
At this time, because the pageattr of im->image is rox,
arch_prepare_bpf_trampoline will read and write im->image, which causes
a fault. as follows:
insmod livepatch-sample.ko # samples/livepatch/livepatch-sample.c
bpftrace -e kretfunc:cmdline_proc_show {}
BUG: unable to handle page fault for address: ffffffffa0206000
PGD 322d067 P4D 322d067 PUD 322e063 PMD 1297e067 PTE d428061
Oops: 0003 [#1] PREEMPT SMP PTI
CPU: 2 PID: 270 Comm: bpftrace Tainted: G E K 6.1.0 #5
RIP: 0010:arch_prepare_bpf_trampoline+0xed/0x8c0
RSP: 0018:ffffc90001083ad8 EFLAGS: 00010202
RAX: ffffffffa0206000 RBX: 0000000000000020 RCX: 0000000000000000
RDX: ffffffffa0206001 RSI: ffffffffa0206000 RDI: 0000000000000030
RBP: ffffc90001083b70 R08: 0000000000000066 R09: ffff88800f51b400
R10: 000000002e72c6e5 R11: 00000000d0a15080 R12: ffff8880110a68c8
R13: 0000000000000000 R14: ffff88800f51b400 R15: ffffffff814fec10
FS: 00007f87bc0dc780(0000) GS:ffff88803e600000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffa0206000 CR3: 0000000010b70000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace: