* [PATCH] debugfs: Fix memleak in debugfs_change_name().
@ 2025-12-08 9:45 Kuniyuki Iwashima
2025-12-08 23:08 ` Greg Kroah-Hartman
2025-12-19 15:44 ` Danilo Krummrich
0 siblings, 2 replies; 3+ messages in thread
From: Kuniyuki Iwashima @ 2025-12-08 9:45 UTC (permalink / raw)
To: Greg Kroah-Hartman, Rafael J. Wysocki, Danilo Krummrich,
Christian Brauner
Cc: NeilBrown, Kuniyuki Iwashima, Kuniyuki Iwashima, linux-kernel,
syzbot+3d7ca9c802c547f8550a
syzbot reported memleak in debugfs_change_name(). [0]
When lookup_noperm_unlocked() fails, new_name is leaked.
Let's fix it by reusing to kfree_const() at the end of
debugfs_change_name().
[0]:
BUG: memory leak
unreferenced object 0xffff8881110bb308 (size 8):
comm "syz.0.17", pid 6090, jiffies 4294942958
hex dump (first 8 bytes):
2e 00 00 00 00 00 00 00 ........
backtrace (crc ecfc7064):
kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]
slab_post_alloc_hook mm/slub.c:4953 [inline]
slab_alloc_node mm/slub.c:5258 [inline]
__do_kmalloc_node mm/slub.c:5651 [inline]
__kmalloc_node_track_caller_noprof+0x3b2/0x670 mm/slub.c:5759
__kmemdup_nul mm/util.c:64 [inline]
kstrdup+0x3c/0x80 mm/util.c:84
kstrdup_const+0x63/0x80 mm/util.c:104
kvasprintf_const+0xca/0x110 lib/kasprintf.c:48
debugfs_change_name+0xf6/0x5d0 fs/debugfs/inode.c:854
cfg80211_dev_rename+0xd8/0x110 net/wireless/core.c:149
nl80211_set_wiphy+0x102/0x1770 net/wireless/nl80211.c:3844
genl_family_rcv_msg_doit+0x11e/0x190 net/netlink/genetlink.c:1115
genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]
genl_rcv_msg+0x2fd/0x440 net/netlink/genetlink.c:1210
netlink_rcv_skb+0x93/0x1d0 net/netlink/af_netlink.c:2550
genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x3a3/0x4f0 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x335/0x6b0 net/netlink/af_netlink.c:1894
sock_sendmsg_nosec net/socket.c:718 [inline]
__sock_sendmsg net/socket.c:733 [inline]
____sys_sendmsg+0x562/0x5a0 net/socket.c:2608
___sys_sendmsg+0xc8/0x130 net/socket.c:2662
__sys_sendmsg+0xc7/0x140 net/socket.c:2694
Fixes: 833d2b3a072f7 ("Add start_renaming_two_dentries()")
Reported-by: syzbot+3d7ca9c802c547f8550a@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/69369d82.a70a0220.38f243.009f.GAE@google.com/
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
---
fs/debugfs/inode.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index 4b263c328ed29..4005d21cf009c 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -841,8 +841,10 @@ int __printf(2, 3) debugfs_change_name(struct dentry *dentry, const char *fmt, .
rd.new_parent = rd.old_parent;
rd.flags = RENAME_NOREPLACE;
target = lookup_noperm_unlocked(&QSTR(new_name), rd.new_parent);
- if (IS_ERR(target))
- return PTR_ERR(target);
+ if (IS_ERR(target)) {
+ error = PTR_ERR(target);
+ goto out_free;
+ }
error = start_renaming_two_dentries(&rd, dentry, target);
if (error) {
@@ -862,6 +864,7 @@ int __printf(2, 3) debugfs_change_name(struct dentry *dentry, const char *fmt, .
out:
dput(rd.old_parent);
dput(target);
+out_free:
kfree_const(new_name);
return error;
}
--
2.52.0.223.gf5cc29aaa4-goog
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] debugfs: Fix memleak in debugfs_change_name().
2025-12-08 9:45 [PATCH] debugfs: Fix memleak in debugfs_change_name() Kuniyuki Iwashima
@ 2025-12-08 23:08 ` Greg Kroah-Hartman
2025-12-19 15:44 ` Danilo Krummrich
1 sibling, 0 replies; 3+ messages in thread
From: Greg Kroah-Hartman @ 2025-12-08 23:08 UTC (permalink / raw)
To: Kuniyuki Iwashima
Cc: Rafael J. Wysocki, Danilo Krummrich, Christian Brauner, NeilBrown,
Kuniyuki Iwashima, linux-kernel, syzbot+3d7ca9c802c547f8550a
On Mon, Dec 08, 2025 at 09:45:45AM +0000, Kuniyuki Iwashima wrote:
> syzbot reported memleak in debugfs_change_name(). [0]
>
> When lookup_noperm_unlocked() fails, new_name is leaked.
>
> Let's fix it by reusing to kfree_const() at the end of
> debugfs_change_name().
>
> [0]:
> BUG: memory leak
> unreferenced object 0xffff8881110bb308 (size 8):
> comm "syz.0.17", pid 6090, jiffies 4294942958
> hex dump (first 8 bytes):
> 2e 00 00 00 00 00 00 00 ........
> backtrace (crc ecfc7064):
> kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]
> slab_post_alloc_hook mm/slub.c:4953 [inline]
> slab_alloc_node mm/slub.c:5258 [inline]
> __do_kmalloc_node mm/slub.c:5651 [inline]
> __kmalloc_node_track_caller_noprof+0x3b2/0x670 mm/slub.c:5759
> __kmemdup_nul mm/util.c:64 [inline]
> kstrdup+0x3c/0x80 mm/util.c:84
> kstrdup_const+0x63/0x80 mm/util.c:104
> kvasprintf_const+0xca/0x110 lib/kasprintf.c:48
> debugfs_change_name+0xf6/0x5d0 fs/debugfs/inode.c:854
> cfg80211_dev_rename+0xd8/0x110 net/wireless/core.c:149
> nl80211_set_wiphy+0x102/0x1770 net/wireless/nl80211.c:3844
> genl_family_rcv_msg_doit+0x11e/0x190 net/netlink/genetlink.c:1115
> genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]
> genl_rcv_msg+0x2fd/0x440 net/netlink/genetlink.c:1210
> netlink_rcv_skb+0x93/0x1d0 net/netlink/af_netlink.c:2550
> genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219
> netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
> netlink_unicast+0x3a3/0x4f0 net/netlink/af_netlink.c:1344
> netlink_sendmsg+0x335/0x6b0 net/netlink/af_netlink.c:1894
> sock_sendmsg_nosec net/socket.c:718 [inline]
> __sock_sendmsg net/socket.c:733 [inline]
> ____sys_sendmsg+0x562/0x5a0 net/socket.c:2608
> ___sys_sendmsg+0xc8/0x130 net/socket.c:2662
> __sys_sendmsg+0xc7/0x140 net/socket.c:2694
>
> Fixes: 833d2b3a072f7 ("Add start_renaming_two_dentries()")
> Reported-by: syzbot+3d7ca9c802c547f8550a@syzkaller.appspotmail.com
> Closes: https://lore.kernel.org/all/69369d82.a70a0220.38f243.009f.GAE@google.com/
> Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
> ---
> fs/debugfs/inode.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
> index 4b263c328ed29..4005d21cf009c 100644
> --- a/fs/debugfs/inode.c
> +++ b/fs/debugfs/inode.c
> @@ -841,8 +841,10 @@ int __printf(2, 3) debugfs_change_name(struct dentry *dentry, const char *fmt, .
> rd.new_parent = rd.old_parent;
> rd.flags = RENAME_NOREPLACE;
> target = lookup_noperm_unlocked(&QSTR(new_name), rd.new_parent);
> - if (IS_ERR(target))
> - return PTR_ERR(target);
> + if (IS_ERR(target)) {
> + error = PTR_ERR(target);
> + goto out_free;
> + }
>
> error = start_renaming_two_dentries(&rd, dentry, target);
> if (error) {
> @@ -862,6 +864,7 @@ int __printf(2, 3) debugfs_change_name(struct dentry *dentry, const char *fmt, .
> out:
> dput(rd.old_parent);
> dput(target);
> +out_free:
> kfree_const(new_name);
> return error;
> }
> --
> 2.52.0.223.gf5cc29aaa4-goog
>
Thanks, I'll queue this up after -rc1 is out.
greg k-h
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] debugfs: Fix memleak in debugfs_change_name().
2025-12-08 9:45 [PATCH] debugfs: Fix memleak in debugfs_change_name() Kuniyuki Iwashima
2025-12-08 23:08 ` Greg Kroah-Hartman
@ 2025-12-19 15:44 ` Danilo Krummrich
1 sibling, 0 replies; 3+ messages in thread
From: Danilo Krummrich @ 2025-12-19 15:44 UTC (permalink / raw)
To: Kuniyuki Iwashima
Cc: Greg Kroah-Hartman, Rafael J. Wysocki, Christian Brauner,
NeilBrown, Kuniyuki Iwashima, linux-kernel,
syzbot+3d7ca9c802c547f8550a
On Mon Dec 8, 2025 at 10:45 AM CET, Kuniyuki Iwashima wrote:
> syzbot reported memleak in debugfs_change_name(). [0]
>
> When lookup_noperm_unlocked() fails, new_name is leaked.
>
> Let's fix it by reusing to kfree_const() at the end of
> debugfs_change_name().
>
> [0]:
> BUG: memory leak
> unreferenced object 0xffff8881110bb308 (size 8):
> comm "syz.0.17", pid 6090, jiffies 4294942958
> hex dump (first 8 bytes):
> 2e 00 00 00 00 00 00 00 ........
> backtrace (crc ecfc7064):
> kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline]
> slab_post_alloc_hook mm/slub.c:4953 [inline]
> slab_alloc_node mm/slub.c:5258 [inline]
> __do_kmalloc_node mm/slub.c:5651 [inline]
> __kmalloc_node_track_caller_noprof+0x3b2/0x670 mm/slub.c:5759
> __kmemdup_nul mm/util.c:64 [inline]
> kstrdup+0x3c/0x80 mm/util.c:84
> kstrdup_const+0x63/0x80 mm/util.c:104
> kvasprintf_const+0xca/0x110 lib/kasprintf.c:48
> debugfs_change_name+0xf6/0x5d0 fs/debugfs/inode.c:854
> cfg80211_dev_rename+0xd8/0x110 net/wireless/core.c:149
> nl80211_set_wiphy+0x102/0x1770 net/wireless/nl80211.c:3844
> genl_family_rcv_msg_doit+0x11e/0x190 net/netlink/genetlink.c:1115
> genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]
> genl_rcv_msg+0x2fd/0x440 net/netlink/genetlink.c:1210
> netlink_rcv_skb+0x93/0x1d0 net/netlink/af_netlink.c:2550
> genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219
> netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
> netlink_unicast+0x3a3/0x4f0 net/netlink/af_netlink.c:1344
> netlink_sendmsg+0x335/0x6b0 net/netlink/af_netlink.c:1894
> sock_sendmsg_nosec net/socket.c:718 [inline]
> __sock_sendmsg net/socket.c:733 [inline]
> ____sys_sendmsg+0x562/0x5a0 net/socket.c:2608
> ___sys_sendmsg+0xc8/0x130 net/socket.c:2662
> __sys_sendmsg+0xc7/0x140 net/socket.c:2694
>
> Fixes: 833d2b3a072f7 ("Add start_renaming_two_dentries()")
> Reported-by: syzbot+3d7ca9c802c547f8550a@syzkaller.appspotmail.com
> Closes: https://lore.kernel.org/all/69369d82.a70a0220.38f243.009f.GAE@google.com/
> Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Applied to driver-core-linus, thanks!
[ Fix minor typo in commit message. - Danilo ]
^ permalink raw reply [flat|nested] 3+ messages in thread
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2025-12-08 9:45 [PATCH] debugfs: Fix memleak in debugfs_change_name() Kuniyuki Iwashima
2025-12-08 23:08 ` Greg Kroah-Hartman
2025-12-19 15:44 ` Danilo Krummrich
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