github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-05-30 10:04:04 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

netconsole: avoid OOB reads, msg is not nul-terminated

Browse Source 
msg passed to netconsole from the console subsystem is not guaranteed
to be nul-terminated. Before recent
commit 7eab73b186 ("netconsole: convert to NBCON console infrastructure")
the message would be placed in printk_shared_pbufs, a static global
buffer, so KASAN had harder time catching OOB accesses. Now we see:

    printk: console [netcon_ext0] enabled
    BUG: KASAN: slab-out-of-bounds in string+0x1f7/0x240
    Read of size 1 at addr ffff88813b6d4c00 by task pr/netcon_ext0/594

    CPU: 65 UID: 0 PID: 594 Comm: pr/netcon_ext0 Not tainted 6.19.0-11754-g4246fd6547c9
    Call Trace:
     kasan_report+0xe4/0x120
     string+0x1f7/0x240
     vsnprintf+0x655/0xba0
     scnprintf+0xba/0x120
     netconsole_write+0x3fe/0xa10
     nbcon_emit_next_record+0x46e/0x860
     nbcon_kthread_func+0x623/0x750

    Allocated by task 1:
     nbcon_alloc+0x1ea/0x450
     register_console+0x26b/0xe10
     init_netconsole+0xbb0/0xda0

    The buggy address belongs to the object at ffff88813b6d4000
                which belongs to the cache kmalloc-4k of size 4096
    The buggy address is located 0 bytes to the right of
                allocated 3072-byte region [ffff88813b6d4000, ffff88813b6d4c00)

Fixes: c62c0a17f9 ("netconsole: Append kernel version to message")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20260219195021.2099699-1-kuba@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Jakub Kicinski 2026-02-19 11:50:21 -08:00 committed by Paolo Abeni
parent bae8a5d2e7
commit 82aec772fc
1 changed files with 2 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
drivers/net/netconsole.c
View File

@ -1679,7 +1679,8 @@ static void send_msg_no_fragmentation(struct netconsole_target *nt,
if (release_len) {
release = init_utsname()->release;
scnprintf(nt->buf, MAX_PRINT_CHUNK, "%s,%s", release, msg);
scnprintf(nt->buf, MAX_PRINT_CHUNK, "%s,%.*s", release,
msg_len, msg);
msg_len += release_len;
} else {
memcpy(nt->buf, msg, msg_len);