Re: [syzbot] KASAN: use-after-free Write in null_skcipher_crypt
From: Grant Likely <hidden>
Date: 2021-08-17 19:09:28
Also in:
linux-bluetooth, lkml, netdev
On 17/08/2021 20:04, Pavel Skripkin wrote:
On 8/17/21 8:24 PM, syzbot wrote:quoted
Hello, syzbot found the following issue on: HEAD commit: a9a507013a6f Merge tag 'ieee802154-for-davem-2021-08-12' o.. git tree: net console output: https://syzkaller.appspot.com/x/log.txt?x=16647ca1300000 kernel config: https://syzkaller.appspot.com/x/.config?x=343fd21f6f4da2d6 dashboard link: https://syzkaller.appspot.com/bug?extid=d2c5e6980bfc84513464 compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14989fe9300000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12b1a779300000 The issue was bisected to: commit 8d2cb3ad31181f050af4d46d6854cf332d1207a9 Author: Calvin Johnson [off-list ref] Date: Fri Jun 11 10:53:55 2021 +0000 of: mdio: Refactor of_mdiobus_register_phy() bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=106b97d6300000 final oops: https://syzkaller.appspot.com/x/report.txt?x=126b97d6300000 console output: https://syzkaller.appspot.com/x/log.txt?x=146b97d6300000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+d2c5e6980bfc84513464@syzkaller.appspotmail.com Fixes: 8d2cb3ad3118 ("of: mdio: Refactor of_mdiobus_register_phy()") ================================================================== BUG: KASAN: use-after-free in memcpy include/linux/fortify-string.h:191 [inline] BUG: KASAN: use-after-free in null_skcipher_crypt+0xa8/0x120 crypto/crypto_null.c:85 Write of size 4096 at addr ffff88801c040000 by task syz-executor554/8455 CPU: 0 PID: 8455 Comm: syz-executor554 Not tainted 5.14.0-rc4-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105 print_address_description.constprop.0.cold+0x6c/0x309 mm/kasan/report.c:233 __kasan_report mm/kasan/report.c:419 [inline] kasan_report.cold+0x83/0xdf mm/kasan/report.c:436 check_region_inline mm/kasan/generic.c:183 [inline] kasan_check_range+0x13d/0x180 mm/kasan/generic.c:189 memcpy+0x39/0x60 mm/kasan/shadow.c:66 memcpy include/linux/fortify-string.h:191 [inline] null_skcipher_crypt+0xa8/0x120 crypto/crypto_null.c:85 crypto_skcipher_encrypt+0xaa/0xf0 crypto/skcipher.c:630 crypto_authenc_encrypt+0x3b4/0x510 crypto/authenc.c:222 crypto_aead_encrypt+0xaa/0xf0 crypto/aead.c:94 esp6_output_tail+0x777/0x1a90 net/ipv6/esp6.c:659 esp6_output+0x4af/0x8a0 net/ipv6/esp6.c:735 xfrm_output_one net/xfrm/xfrm_output.c:552 [inline] xfrm_output_resume+0x2997/0x5ae0 net/xfrm/xfrm_output.c:587 xfrm_output2 net/xfrm/xfrm_output.c:614 [inline] xfrm_output+0x2e7/0xff0 net/xfrm/xfrm_output.c:744 __xfrm6_output+0x4c3/0x1260 net/ipv6/xfrm6_output.c:87 NF_HOOK_COND include/linux/netfilter.h:296 [inline] xfrm6_output+0x117/0x550 net/ipv6/xfrm6_output.c:92 dst_output include/net/dst.h:448 [inline] ip6_local_out+0xaf/0x1a0 net/ipv6/output_core.c:161 ip6_send_skb+0xb7/0x340 net/ipv6/ip6_output.c:1935 ip6_push_pending_frames+0xdd/0x100 net/ipv6/ip6_output.c:1955 rawv6_push_pending_frames net/ipv6/raw.c:613 [inline] rawv6_sendmsg+0x2a87/0x3990 net/ipv6/raw.c:956 inet_sendmsg+0x99/0xe0 net/ipv4/af_inet.c:821 sock_sendmsg_nosec net/socket.c:703 [inline] sock_sendmsg+0xcf/0x120 net/socket.c:723 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2392 ___sys_sendmsg+0xf3/0x170 net/socket.c:2446 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2475 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x43f4b9 Code: 1d 01 00 85 c0 b8 00 00 00 00 48 0f 44 c3 5b c3 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffc1e9cfff8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 0000000000400488 RCX: 000000000043f4b9 RDX: 0000000000000000 RSI: 0000000020000500 RDI: 0000000000000004 RBP: 0000000000000005 R08: 6c616b7a79732f2e R09: 6c616b7a79732f2e R10: 00000000000000e8 R11: 0000000000000246 R12: 00000000004034b0 R13: 0000000000000000 R14: 00000000004ad018 R15: 0000000000400488 Allocated by task 1: kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38 kasan_set_track mm/kasan/common.c:46 [inline] set_alloc_info mm/kasan/common.c:434 [inline] __kasan_slab_alloc+0x84/0xa0 mm/kasan/common.c:467 kasan_slab_alloc include/linux/kasan.h:254 [inline] slab_post_alloc_hook mm/slab.h:519 [inline] slab_alloc_node mm/slub.c:2956 [inline] slab_alloc mm/slub.c:2964 [inline] kmem_cache_alloc+0x285/0x4a0 mm/slub.c:2969 getname_flags.part.0+0x50/0x4f0 fs/namei.c:138 getname_flags fs/namei.c:2747 [inline] user_path_at_empty+0xa1/0x100 fs/namei.c:2747 user_path_at include/linux/namei.h:57 [inline] vfs_statx+0x142/0x390 fs/stat.c:203 vfs_fstatat fs/stat.c:225 [inline] vfs_lstat include/linux/fs.h:3386 [inline] __do_sys_newlstat+0x91/0x110 fs/stat.c:380 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae Freed by task 1: kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38 kasan_set_track+0x1c/0x30 mm/kasan/common.c:46 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:360 ____kasan_slab_free mm/kasan/common.c:366 [inline] ____kasan_slab_free mm/kasan/common.c:328 [inline] __kasan_slab_free+0xfb/0x130 mm/kasan/common.c:374 kasan_slab_free include/linux/kasan.h:230 [inline] slab_free_hook mm/slub.c:1625 [inline] slab_free_freelist_hook+0xdf/0x240 mm/slub.c:1650 slab_free mm/slub.c:3210 [inline] kmem_cache_free+0x8a/0x5b0 mm/slub.c:3226 putname+0xe1/0x120 fs/namei.c:259(*)quoted
filename_lookup+0x3df/0x5b0 fs/namei.c:2477 user_path_at include/linux/namei.h:57 [inline] vfs_statx+0x142/0x390 fs/stat.c:203 vfs_fstatat fs/stat.c:225 [inline] vfs_lstat include/linux/fs.h:3386 [inline] __do_sys_newlstat+0x91/0x110 fs/stat.c:380 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae+CC Dmitry I think, it was caused by 9d96ea38873f ("namei: change filename_parentat() calling conventions"). Now what looks strange to me Upstream version: static struct filename *filename_parentat(...) { ... retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); ... if (likely(!retval)) { *last = nd.last; *type = nd.last_type; audit_inode(name, parent->dentry, AUDIT_INODE_PARENT); } else { putname(name); <-- putting name if retval if not-zero name = ERR_PTR(retval); } } Linux-next version: static int __filename_parentat(...) { retval = path_parentat(&nd, flags | LOOKUP_RCU, parent); ... if (likely(!retval)) { *last = nd.last; *type = nd.last_type; audit_inode(name, parent->dentry, AUDIT_INODE_PARENT); } restore_nameidata(); return retval; } static int filename_parentat(...) { int retval = __filename_parentat(...); putname(name); <-- always putting the name return retval; } And bug report says, that name was freed by this put (*) I guess, we should do smth like: if (retval) putname(name); I didn't dig into details, because Dmitry's patch series was really huge, so it's just for thoughts ;)
Yup, that looks like the correct fix to me. g.
With regards, Pavel Skripkin
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