Re: KASAN: use-after-free Read in seq_escape
On Sun, Sep 30, 2018 at 11:58:02PM -0700, syzbot wrote: > Hello, > > syzbot found the following crash on: > > HEAD commit:17b57b1883c1 Linux 4.19-rc6 > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=1672d71140 > kernel config: https://syzkaller.appspot.com/x/.config?x=c0af03fe452b65fb > dashboard link: https://syzkaller.appspot.com/bug?extid=a2872d6feea6918008a9 > compiler: gcc (GCC) 8.0.1 20180413 (experimental) This should be fixed with the following patch. - Ted >From 89cc85e761c5b905b1a61cb85440bf9b5e841c80 Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Tue, 2 Oct 2018 10:40:57 -0400 Subject: [PATCH] ext4: fix use-after-free race in ext4_remount()'s error path It's possible for ext4_show_quota_options() to try reading s_qf_names[i] while it is being modified by ext4_remount() --- most notably, in ext4_remount's error path when the original values of the quota file name gets restored. Reported-by: syzbot+a2872d6feea691800...@syzkaller.appspotmail.com Signed-off-by: Theodore Ts'o Cc: sta...@kernel.org --- fs/ext4/super.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/ext4/super.c b/fs/ext4/super.c index faf293ed8060..11a1bfae0937 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -2048,11 +2048,13 @@ static inline void ext4_show_quota_options(struct seq_file *seq, seq_printf(seq, ",jqfmt=%s", fmtname); } + down_read(>s_umount); if (sbi->s_qf_names[USRQUOTA]) seq_show_option(seq, "usrjquota", sbi->s_qf_names[USRQUOTA]); if (sbi->s_qf_names[GRPQUOTA]) seq_show_option(seq, "grpjquota", sbi->s_qf_names[GRPQUOTA]); + up_read(>s_umount); #endif } -- 2.18.0.rc0
Re: KASAN: use-after-free Read in seq_escape
On Sun, Sep 30, 2018 at 11:58:02PM -0700, syzbot wrote: > Hello, > > syzbot found the following crash on: > > HEAD commit:17b57b1883c1 Linux 4.19-rc6 > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=1672d71140 > kernel config: https://syzkaller.appspot.com/x/.config?x=c0af03fe452b65fb > dashboard link: https://syzkaller.appspot.com/bug?extid=a2872d6feea6918008a9 > compiler: gcc (GCC) 8.0.1 20180413 (experimental) This should be fixed with the following patch. - Ted >From 89cc85e761c5b905b1a61cb85440bf9b5e841c80 Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Tue, 2 Oct 2018 10:40:57 -0400 Subject: [PATCH] ext4: fix use-after-free race in ext4_remount()'s error path It's possible for ext4_show_quota_options() to try reading s_qf_names[i] while it is being modified by ext4_remount() --- most notably, in ext4_remount's error path when the original values of the quota file name gets restored. Reported-by: syzbot+a2872d6feea691800...@syzkaller.appspotmail.com Signed-off-by: Theodore Ts'o Cc: sta...@kernel.org --- fs/ext4/super.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/ext4/super.c b/fs/ext4/super.c index faf293ed8060..11a1bfae0937 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -2048,11 +2048,13 @@ static inline void ext4_show_quota_options(struct seq_file *seq, seq_printf(seq, ",jqfmt=%s", fmtname); } + down_read(>s_umount); if (sbi->s_qf_names[USRQUOTA]) seq_show_option(seq, "usrjquota", sbi->s_qf_names[USRQUOTA]); if (sbi->s_qf_names[GRPQUOTA]) seq_show_option(seq, "grpjquota", sbi->s_qf_names[GRPQUOTA]); + up_read(>s_umount); #endif } -- 2.18.0.rc0
KASAN: use-after-free Read in seq_escape
Hello, syzbot found the following crash on: HEAD commit:17b57b1883c1 Linux 4.19-rc6 git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=1672d71140 kernel config: https://syzkaller.appspot.com/x/.config?x=c0af03fe452b65fb dashboard link: https://syzkaller.appspot.com/bug?extid=a2872d6feea6918008a9 compiler: gcc (GCC) 8.0.1 20180413 (experimental) Unfortunately, I don't have any reproducer for this crash yet. IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+a2872d6feea691800...@syzkaller.appspotmail.com (unnamed net_device) (uninitialized): option active_slave: mode dependency failed, not supported in mode balance-rr(0) IPVS: ftp: loaded support on port[0] = 21 EXT4-fs (sda1): journaled quota format not specified == BUG: KASAN: use-after-free in strlen+0x83/0xa0 lib/string.c:482 Read of size 1 at addr 8801ce9a9540 by task syz-executor2/486 CPU: 1 PID: 486 Comm: syz-executor2 Not tainted 4.19.0-rc6+ #39 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 (unnamed net_device) (uninitialized): option active_slave: mode dependency failed, not supported in mode balance-rr(0) Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1c4/0x2b4 lib/dump_stack.c:113 print_address_description.cold.8+0x9/0x1ff mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report.cold.9+0x242/0x309 mm/kasan/report.c:412 __asan_report_load1_noabort+0x14/0x20 mm/kasan/report.c:430 strlen+0x83/0xa0 lib/string.c:482 strlen include/linux/string.h:267 [inline] string_escape_str include/linux/string_helpers.h:66 [inline] seq_escape+0xd5/0x240 fs/seq_file.c:381 seq_show_option include/linux/seq_file.h:185 [inline] ext4_show_quota_options fs/ext4/super.c:2051 [inline] _ext4_show_options+0xcef/0x18f0 fs/ext4/super.c:2151 ext4_show_options+0x41/0x50 fs/ext4/super.c:2157 show_mountinfo+0x674/0x9b0 fs/proc_namespace.c:187 m_show+0x65/0x80 fs/namespace.c:1280 seq_read+0x4af/0x1150 fs/seq_file.c:229 do_loop_readv_writev fs/read_write.c:700 [inline] do_iter_read+0x4a3/0x650 fs/read_write.c:924 vfs_readv+0x175/0x1c0 fs/read_write.c:986 do_preadv+0x1cc/0x280 fs/read_write.c:1070 __do_sys_preadv fs/read_write.c:1120 [inline] __se_sys_preadv fs/read_write.c:1115 [inline] __x64_sys_preadv+0x9a/0xf0 fs/read_write.c:1115 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x457579 Code: 1d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 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 0f 83 eb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:7f8a6dc50c78 EFLAGS: 0246 ORIG_RAX: 0127 RAX: ffda RBX: 0004 RCX: 00457579 RDX: 1181 RSI: 2480 RDI: 0005 RBP: 0072bf00 R08: R09: R10: R11: 0246 R12: 7f8a6dc516d4 R13: 004c309c R14: 004d4a40 R15: Allocated by task 493: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553 __do_kmalloc mm/slab.c:3718 [inline] __kmalloc+0x14e/0x760 mm/slab.c:3727 kmalloc include/linux/slab.h:518 [inline] match_strdup+0x5e/0xa0 lib/parser.c:331 set_qf_name+0x14b/0x3e0 fs/ext4/super.c:1548 handle_mount_opt fs/ext4/super.c:1718 [inline] parse_options+0xd3e/0x29c0 fs/ext4/super.c:1979 ext4_remount+0x693/0x2640 fs/ext4/super.c:5139 do_remount_sb+0x350/0x7b0 fs/super.c:888 do_remount fs/namespace.c:2278 [inline] do_mount+0x1513/0x31f0 fs/namespace.c:2778 ksys_mount+0x12d/0x140 fs/namespace.c:3003 __do_sys_mount fs/namespace.c:3017 [inline] __se_sys_mount fs/namespace.c:3014 [inline] __x64_sys_mount+0xbe/0x150 fs/namespace.c:3014 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 493: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 __cache_free mm/slab.c:3498 [inline] kfree+0xcf/0x230 mm/slab.c:3813 ext4_remount+0x11ec/0x2640 fs/ext4/super.c:5355 do_remount_sb+0x350/0x7b0 fs/super.c:888 do_remount fs/namespace.c:2278 [inline] do_mount+0x1513/0x31f0 fs/namespace.c:2778 ksys_mount+0x12d/0x140 fs/namespace.c:3003 __do_sys_mount fs/namespace.c:3017 [inline] __se_sys_mount fs/namespace.c:3014 [inline] __x64_sys_mount+0xbe/0x150 fs/namespace.c:3014 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at 8801ce9a9540 which belongs to the cache kmalloc-32 of size 32 The buggy address is located 0 bytes
KASAN: use-after-free Read in seq_escape
Hello, syzbot found the following crash on: HEAD commit:17b57b1883c1 Linux 4.19-rc6 git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=1672d71140 kernel config: https://syzkaller.appspot.com/x/.config?x=c0af03fe452b65fb dashboard link: https://syzkaller.appspot.com/bug?extid=a2872d6feea6918008a9 compiler: gcc (GCC) 8.0.1 20180413 (experimental) Unfortunately, I don't have any reproducer for this crash yet. IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+a2872d6feea691800...@syzkaller.appspotmail.com (unnamed net_device) (uninitialized): option active_slave: mode dependency failed, not supported in mode balance-rr(0) IPVS: ftp: loaded support on port[0] = 21 EXT4-fs (sda1): journaled quota format not specified == BUG: KASAN: use-after-free in strlen+0x83/0xa0 lib/string.c:482 Read of size 1 at addr 8801ce9a9540 by task syz-executor2/486 CPU: 1 PID: 486 Comm: syz-executor2 Not tainted 4.19.0-rc6+ #39 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 (unnamed net_device) (uninitialized): option active_slave: mode dependency failed, not supported in mode balance-rr(0) Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1c4/0x2b4 lib/dump_stack.c:113 print_address_description.cold.8+0x9/0x1ff mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report.cold.9+0x242/0x309 mm/kasan/report.c:412 __asan_report_load1_noabort+0x14/0x20 mm/kasan/report.c:430 strlen+0x83/0xa0 lib/string.c:482 strlen include/linux/string.h:267 [inline] string_escape_str include/linux/string_helpers.h:66 [inline] seq_escape+0xd5/0x240 fs/seq_file.c:381 seq_show_option include/linux/seq_file.h:185 [inline] ext4_show_quota_options fs/ext4/super.c:2051 [inline] _ext4_show_options+0xcef/0x18f0 fs/ext4/super.c:2151 ext4_show_options+0x41/0x50 fs/ext4/super.c:2157 show_mountinfo+0x674/0x9b0 fs/proc_namespace.c:187 m_show+0x65/0x80 fs/namespace.c:1280 seq_read+0x4af/0x1150 fs/seq_file.c:229 do_loop_readv_writev fs/read_write.c:700 [inline] do_iter_read+0x4a3/0x650 fs/read_write.c:924 vfs_readv+0x175/0x1c0 fs/read_write.c:986 do_preadv+0x1cc/0x280 fs/read_write.c:1070 __do_sys_preadv fs/read_write.c:1120 [inline] __se_sys_preadv fs/read_write.c:1115 [inline] __x64_sys_preadv+0x9a/0xf0 fs/read_write.c:1115 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x457579 Code: 1d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 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 0f 83 eb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:7f8a6dc50c78 EFLAGS: 0246 ORIG_RAX: 0127 RAX: ffda RBX: 0004 RCX: 00457579 RDX: 1181 RSI: 2480 RDI: 0005 RBP: 0072bf00 R08: R09: R10: R11: 0246 R12: 7f8a6dc516d4 R13: 004c309c R14: 004d4a40 R15: Allocated by task 493: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553 __do_kmalloc mm/slab.c:3718 [inline] __kmalloc+0x14e/0x760 mm/slab.c:3727 kmalloc include/linux/slab.h:518 [inline] match_strdup+0x5e/0xa0 lib/parser.c:331 set_qf_name+0x14b/0x3e0 fs/ext4/super.c:1548 handle_mount_opt fs/ext4/super.c:1718 [inline] parse_options+0xd3e/0x29c0 fs/ext4/super.c:1979 ext4_remount+0x693/0x2640 fs/ext4/super.c:5139 do_remount_sb+0x350/0x7b0 fs/super.c:888 do_remount fs/namespace.c:2278 [inline] do_mount+0x1513/0x31f0 fs/namespace.c:2778 ksys_mount+0x12d/0x140 fs/namespace.c:3003 __do_sys_mount fs/namespace.c:3017 [inline] __se_sys_mount fs/namespace.c:3014 [inline] __x64_sys_mount+0xbe/0x150 fs/namespace.c:3014 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 493: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 __cache_free mm/slab.c:3498 [inline] kfree+0xcf/0x230 mm/slab.c:3813 ext4_remount+0x11ec/0x2640 fs/ext4/super.c:5355 do_remount_sb+0x350/0x7b0 fs/super.c:888 do_remount fs/namespace.c:2278 [inline] do_mount+0x1513/0x31f0 fs/namespace.c:2778 ksys_mount+0x12d/0x140 fs/namespace.c:3003 __do_sys_mount fs/namespace.c:3017 [inline] __se_sys_mount fs/namespace.c:3014 [inline] __x64_sys_mount+0xbe/0x150 fs/namespace.c:3014 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at 8801ce9a9540 which belongs to the cache kmalloc-32 of size 32 The buggy address is located 0 bytes
