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| author | Chengfeng Ye <nicoyip.dev@gmail.com> | 2026-07-19 22:57:40 +0800 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2026-07-24 16:29:20 -0700 |
| commit | 817ff6efdb7f484ea547218e11e17d8e43daa3b4 (patch) | |
| tree | d805831371f4124eb34a8547a03e4508e257f579 | |
| parent | a3729e0df005a936ceb3c2b0d167f01a2b03f970 (diff) | |
net: pktgen: fix proc entry use-after-free
pktgen_change_name() replaces pkt_dev->entry while holding t->if_lock.
pktgen_remove_device() removes the same entry before
_rem_dev_from_if_list() takes that lock.
This allows the following interleaving:
CPU 0 (NETDEV_CHANGENAME) CPU 1 (kpktgend)
if_lock(t)
proc_remove(pkt_dev->entry)
proc_remove(pkt_dev->entry)
pkt_dev->entry = proc_create_data(...)
if_unlock(t)
The kthread can pass the stale proc_dir_entry to proc_remove() after the
rename path has freed it. A reproducer with a widened race window reports:
BUG: KASAN: slab-use-after-free in proc_remove+0x78/0x80
Read of size 8 at addr ffff8881478fea70 by task kpktgend_0/67
Call Trace:
proc_remove+0x78/0x80
pktgen_remove_device.isra.0+0x11c/0x4c0
pktgen_thread_worker+0x1214/0x6bc0
kthread+0x2c6/0x3b0
Allocated by task 95:
__proc_create+0x204/0x790
proc_create_data+0x72/0xe0
pktgen_thread_write+0xd61/0x1510
Freed by task 28:
kmem_cache_free+0xcb/0x3d0
proc_free_inode+0x5b/0x80
rcu_core+0x50a/0x1850
The buggy address belongs to the object at ffff8881478fea00
which belongs to the cache proc_dir_entry of size 192
Move proc_remove() into the if_lock-protected list removal helper. Keep it
before list_del_rcu() to preserve the ordering required by add_device().
The rename path must then finish replacing the entry before removal, or
it observes that the device is no longer on the list.
Fixes: 39df232f1a9b ("[PKTGEN]: fix device name handling")
Cc: stable@vger.kernel.org
Signed-off-by: Chengfeng Ye <nicoyip.dev@gmail.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20260719145740.2888967-1-nicoyip.dev@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
| -rw-r--r-- | net/core/pktgen.c | 4 |
1 files changed, 1 insertions, 3 deletions
diff --git a/net/core/pktgen.c b/net/core/pktgen.c index 8e185b318288..ee64f3012321 100644 --- a/net/core/pktgen.c +++ b/net/core/pktgen.c @@ -3972,6 +3972,7 @@ static void _rem_dev_from_if_list(struct pktgen_thread *t, struct pktgen_dev *p; if_lock(t); + proc_remove(pkt_dev->entry); list_for_each_safe(q, n, &t->if_list) { p = list_entry(q, struct pktgen_dev, list); if (p == pkt_dev) @@ -4001,9 +4002,6 @@ static int pktgen_remove_device(struct pktgen_thread *t, * list to determine if interface already exist, avoid race * with proc_create_data() */ - proc_remove(pkt_dev->entry); - - /* And update the thread if_list */ _rem_dev_from_if_list(t, pkt_dev); #ifdef CONFIG_XFRM |