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24 Aug 2021 03:48:03 -0700 (PDT) Received: from [192.168.1.11] ([46.235.66.127]) by smtp.gmail.com with ESMTPSA id y10sm1881615lfh.40.2021.08.24.03.48.02 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 24 Aug 2021 03:48:02 -0700 (PDT) Subject: Re: [syzbot] KASAN: use-after-free Write in null_skcipher_crypt From: Pavel Skripkin To: syzbot , calvin.johnson@oss.nxp.com, davem@davemloft.net, grant.likely@arm.com, herbert@gondor.apana.org.au, ioana.ciornei@nxp.com, johan.hedberg@gmail.com, kuba@kernel.org, linux-bluetooth@vger.kernel.org, linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, luiz.dentz@gmail.com, marcel@holtmann.org, netdev@vger.kernel.org, syzkaller-bugs@googlegroups.com, dkadashev@gmail.com, viro@zeniv.linux.org.uk References: <000000000000c910c305c9c4962e@google.com> <7f4eed54-4e40-2e85-eaaa-95b1864c6649@gmail.com> Message-ID: <2e7d8a38-da4b-a79b-2482-f5d05a4dbbfd@gmail.com> Date: Tue, 24 Aug 2021 13:48:01 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: <7f4eed54-4e40-2e85-eaaa-95b1864c6649@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/17/21 10:04 PM, Pavel Skripkin wrote: > On 8/17/21 8:24 PM, syzbot wrote: >> 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 >> 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 > > (*) > >> 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 ;) > > > +CC Alexander, since people start getting this error while testing patches on top of linux-next With regards, Pavel Skripkin