Re: [syzbot] [hams?] KASAN: slab-use-after-free Read in nr_add_node
From: Brahmajit Das <hidden>
Date: 2025-10-19 05:03:14
Also in:
linux-hams, lkml
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
On 18.10.2025 13:37, syzbot wrote:
syzbot has found a reproducer for the following issue on: HEAD commit: f406055cb18c Merge tag 'arm64-fixes' of git://git.kernel.o.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=11cf767c580000 kernel config: https://syzkaller.appspot.com/x/.config?x=f3e7b5a3627a90dd dashboard link: https://syzkaller.appspot.com/bug?extid=2860e75836a08b172755 compiler: gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=155f1de2580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12b6b52f980000 Downloadable assets: disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-f406055c.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/a4db2a99bfb1/vmlinux-f406055c.xz kernel image: https://storage.googleapis.com/syzbot-assets/91d1ca420bac/bzImage-f406055c.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+2860e75836a08b172755@syzkaller.appspotmail.com ================================================================== BUG: KASAN: slab-use-after-free in nr_add_node+0x25db/0x2c00 net/netrom/nr_route.c:248 Read of size 4 at addr ffff888054b8cc30 by task syz.3.7839/22393
#syz test
diff --git a/net/netrom/nr_route.c b/net/netrom/nr_route.c
index b94cb2ffbaf8..5fa7d9febbbb 100644
--- a/net/netrom/nr_route.c
+++ b/net/netrom/nr_route.c@@ -245,7 +245,9 @@ static int __must_check nr_add_node(ax25_address *nr, const char *mnemonic, nr_node->routes[2].neighbour->count--; nr_neigh_put(nr_node->routes[2].neighbour); - if (nr_node->routes[2].neighbour->count == 0 && !nr_node->routes[2].neighbour->locked) + if (nr_node->routes[2].neighbour && + nr_node->routes[2].neighbour->count == 0 && + !nr_node->routes[2].neighbour->locked) nr_remove_neigh(nr_node->routes[2].neighbour); nr_node->routes[2].quality = quality;
--
Regards,
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