| Message ID | 20190812181429.11444-1-fdmanana@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Btrfs: fix use-after-free when using the tree modification log | expand |
On 12.08.19 г. 21:14 ч., fdmanana@kernel.org wrote: > From: Filipe Manana <fdmanana@suse.com> > > At ctree.c:get_old_root(), we are accessing a root's header owner field > after we have freed the respective extent buffer. This results in an > use-after-free that can lead to crashes, and when CONFIG_DEBUG_PAGEALLOC > is set, results in a stack trace like the following: > > [ 3876.799331] stack segment: 0000 [#1] SMP DEBUG_PAGEALLOC PTI > [ 3876.799363] CPU: 0 PID: 15436 Comm: pool Not tainted 5.3.0-rc3-btrfs-next-54 #1 > [ 3876.799385] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-0-ga698c8995f-prebuilt.qemu.org 04/01/2014 > [ 3876.799433] RIP: 0010:btrfs_search_old_slot+0x652/0xd80 [btrfs] > (...) > [ 3876.799502] RSP: 0018:ffff9f08c1a2f9f0 EFLAGS: 00010286 > [ 3876.799518] RAX: ffff8dd300000000 RBX: ffff8dd85a7a9348 RCX: 000000038da26000 > [ 3876.799538] RDX: 0000000000000000 RSI: ffffe522ce368980 RDI: 0000000000000246 > [ 3876.799559] RBP: dae1922adadad000 R08: 0000000008020000 R09: ffffe522c0000000 > [ 3876.799579] R10: ffff8dd57fd788c8 R11: 000000007511b030 R12: ffff8dd781ddc000 > [ 3876.799599] R13: ffff8dd9e6240578 R14: ffff8dd6896f7a88 R15: ffff8dd688cf90b8 > [ 3876.799620] FS: 00007f23ddd97700(0000) GS:ffff8dda20200000(0000) knlGS:0000000000000000 > [ 3876.799643] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 3876.799660] CR2: 00007f23d4024000 CR3: 0000000710bb0005 CR4: 00000000003606f0 > [ 3876.799682] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > [ 3876.799703] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > [ 3876.799723] Call Trace: > [ 3876.799735] ? do_raw_spin_unlock+0x49/0xc0 > [ 3876.799749] ? _raw_spin_unlock+0x24/0x30 > [ 3876.799779] resolve_indirect_refs+0x1eb/0xc80 [btrfs] > [ 3876.799810] find_parent_nodes+0x38d/0x1180 [btrfs] > [ 3876.799841] btrfs_check_shared+0x11a/0x1d0 [btrfs] > [ 3876.799870] ? extent_fiemap+0x598/0x6e0 [btrfs] > [ 3876.799895] extent_fiemap+0x598/0x6e0 [btrfs] > [ 3876.799913] do_vfs_ioctl+0x45a/0x700 > [ 3876.799926] ksys_ioctl+0x70/0x80 > [ 3876.799938] ? trace_hardirqs_off_thunk+0x1a/0x20 > [ 3876.799953] __x64_sys_ioctl+0x16/0x20 > [ 3876.799965] do_syscall_64+0x62/0x220 > [ 3876.799977] entry_SYSCALL_64_after_hwframe+0x49/0xbe > [ 3876.799993] RIP: 0033:0x7f23e0013dd7 > (...) > [ 3876.800056] RSP: 002b:00007f23ddd96ca8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 > [ 3876.800078] RAX: ffffffffffffffda RBX: 00007f23d80210f8 RCX: 00007f23e0013dd7 > [ 3876.800099] RDX: 00007f23d80210f8 RSI: 00000000c020660b RDI: 0000000000000003 > [ 3876.800626] RBP: 000055fa2a2a2440 R08: 0000000000000000 R09: 00007f23ddd96d7c > [ 3876.801143] R10: 00007f23d8022000 R11: 0000000000000246 R12: 00007f23ddd96d80 > [ 3876.801662] R13: 00007f23ddd96d78 R14: 00007f23d80210f0 R15: 00007f23ddd96d80 > (...) > [ 3876.805107] ---[ end trace e53161e179ef04f9 ]--- > > Fix that by saving the root's header owner field into a local variable > before freeing the root's extent buffer, and then use that local variable > when needed. > > Fixes: 30b0463a9394d9 ("Btrfs: fix accessing the root pointer in tree mod log functions") > CC: stable@vger.kernel.org # 3.10+ > Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: Nikolay Borisov <nborisov@suse.com>
On 13/8/19 2:14 AM, fdmanana@kernel.org wrote: > From: Filipe Manana <fdmanana@suse.com> > > At ctree.c:get_old_root(), we are accessing a root's header owner field > after we have freed the respective extent buffer. This results in an > use-after-free that can lead to crashes, and when CONFIG_DEBUG_PAGEALLOC > is set, results in a stack trace like the following: > > [ 3876.799331] stack segment: 0000 [#1] SMP DEBUG_PAGEALLOC PTI > [ 3876.799363] CPU: 0 PID: 15436 Comm: pool Not tainted 5.3.0-rc3-btrfs-next-54 #1 > [ 3876.799385] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-0-ga698c8995f-prebuilt.qemu.org 04/01/2014 > [ 3876.799433] RIP: 0010:btrfs_search_old_slot+0x652/0xd80 [btrfs] > (...) > [ 3876.799502] RSP: 0018:ffff9f08c1a2f9f0 EFLAGS: 00010286 > [ 3876.799518] RAX: ffff8dd300000000 RBX: ffff8dd85a7a9348 RCX: 000000038da26000 > [ 3876.799538] RDX: 0000000000000000 RSI: ffffe522ce368980 RDI: 0000000000000246 > [ 3876.799559] RBP: dae1922adadad000 R08: 0000000008020000 R09: ffffe522c0000000 > [ 3876.799579] R10: ffff8dd57fd788c8 R11: 000000007511b030 R12: ffff8dd781ddc000 > [ 3876.799599] R13: ffff8dd9e6240578 R14: ffff8dd6896f7a88 R15: ffff8dd688cf90b8 > [ 3876.799620] FS: 00007f23ddd97700(0000) GS:ffff8dda20200000(0000) knlGS:0000000000000000 > [ 3876.799643] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 3876.799660] CR2: 00007f23d4024000 CR3: 0000000710bb0005 CR4: 00000000003606f0 > [ 3876.799682] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > [ 3876.799703] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > [ 3876.799723] Call Trace: > [ 3876.799735] ? do_raw_spin_unlock+0x49/0xc0 > [ 3876.799749] ? _raw_spin_unlock+0x24/0x30 > [ 3876.799779] resolve_indirect_refs+0x1eb/0xc80 [btrfs] > [ 3876.799810] find_parent_nodes+0x38d/0x1180 [btrfs] > [ 3876.799841] btrfs_check_shared+0x11a/0x1d0 [btrfs] > [ 3876.799870] ? extent_fiemap+0x598/0x6e0 [btrfs] > [ 3876.799895] extent_fiemap+0x598/0x6e0 [btrfs] > [ 3876.799913] do_vfs_ioctl+0x45a/0x700 > [ 3876.799926] ksys_ioctl+0x70/0x80 > [ 3876.799938] ? trace_hardirqs_off_thunk+0x1a/0x20 > [ 3876.799953] __x64_sys_ioctl+0x16/0x20 > [ 3876.799965] do_syscall_64+0x62/0x220 > [ 3876.799977] entry_SYSCALL_64_after_hwframe+0x49/0xbe > [ 3876.799993] RIP: 0033:0x7f23e0013dd7 > (...) > [ 3876.800056] RSP: 002b:00007f23ddd96ca8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 > [ 3876.800078] RAX: ffffffffffffffda RBX: 00007f23d80210f8 RCX: 00007f23e0013dd7 > [ 3876.800099] RDX: 00007f23d80210f8 RSI: 00000000c020660b RDI: 0000000000000003 > [ 3876.800626] RBP: 000055fa2a2a2440 R08: 0000000000000000 R09: 00007f23ddd96d7c > [ 3876.801143] R10: 00007f23d8022000 R11: 0000000000000246 R12: 00007f23ddd96d80 > [ 3876.801662] R13: 00007f23ddd96d78 R14: 00007f23d80210f0 R15: 00007f23ddd96d80 > (...) > [ 3876.805107] ---[ end trace e53161e179ef04f9 ]--- > > Fix that by saving the root's header owner field into a local variable > before freeing the root's extent buffer, and then use that local variable > when needed. > > Fixes: 30b0463a9394d9 ("Btrfs: fix accessing the root pointer in tree mod log functions") > CC: stable@vger.kernel.org # 3.10+ > Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: Anand Jain <anand.jain@oracle.com> Thanks, Anand
On Mon, Aug 12, 2019 at 07:14:29PM +0100, fdmanana@kernel.org wrote: > From: Filipe Manana <fdmanana@suse.com> > > At ctree.c:get_old_root(), we are accessing a root's header owner field > after we have freed the respective extent buffer. This results in an > use-after-free that can lead to crashes, and when CONFIG_DEBUG_PAGEALLOC > is set, results in a stack trace like the following: > > [ 3876.799331] stack segment: 0000 [#1] SMP DEBUG_PAGEALLOC PTI > [ 3876.799363] CPU: 0 PID: 15436 Comm: pool Not tainted 5.3.0-rc3-btrfs-next-54 #1 > [ 3876.799385] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-0-ga698c8995f-prebuilt.qemu.org 04/01/2014 > [ 3876.799433] RIP: 0010:btrfs_search_old_slot+0x652/0xd80 [btrfs] > (...) > [ 3876.799502] RSP: 0018:ffff9f08c1a2f9f0 EFLAGS: 00010286 > [ 3876.799518] RAX: ffff8dd300000000 RBX: ffff8dd85a7a9348 RCX: 000000038da26000 > [ 3876.799538] RDX: 0000000000000000 RSI: ffffe522ce368980 RDI: 0000000000000246 > [ 3876.799559] RBP: dae1922adadad000 R08: 0000000008020000 R09: ffffe522c0000000 > [ 3876.799579] R10: ffff8dd57fd788c8 R11: 000000007511b030 R12: ffff8dd781ddc000 > [ 3876.799599] R13: ffff8dd9e6240578 R14: ffff8dd6896f7a88 R15: ffff8dd688cf90b8 > [ 3876.799620] FS: 00007f23ddd97700(0000) GS:ffff8dda20200000(0000) knlGS:0000000000000000 > [ 3876.799643] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 3876.799660] CR2: 00007f23d4024000 CR3: 0000000710bb0005 CR4: 00000000003606f0 > [ 3876.799682] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > [ 3876.799703] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > [ 3876.799723] Call Trace: > [ 3876.799735] ? do_raw_spin_unlock+0x49/0xc0 > [ 3876.799749] ? _raw_spin_unlock+0x24/0x30 > [ 3876.799779] resolve_indirect_refs+0x1eb/0xc80 [btrfs] > [ 3876.799810] find_parent_nodes+0x38d/0x1180 [btrfs] > [ 3876.799841] btrfs_check_shared+0x11a/0x1d0 [btrfs] > [ 3876.799870] ? extent_fiemap+0x598/0x6e0 [btrfs] > [ 3876.799895] extent_fiemap+0x598/0x6e0 [btrfs] > [ 3876.799913] do_vfs_ioctl+0x45a/0x700 > [ 3876.799926] ksys_ioctl+0x70/0x80 > [ 3876.799938] ? trace_hardirqs_off_thunk+0x1a/0x20 > [ 3876.799953] __x64_sys_ioctl+0x16/0x20 > [ 3876.799965] do_syscall_64+0x62/0x220 > [ 3876.799977] entry_SYSCALL_64_after_hwframe+0x49/0xbe > [ 3876.799993] RIP: 0033:0x7f23e0013dd7 > (...) > [ 3876.800056] RSP: 002b:00007f23ddd96ca8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 > [ 3876.800078] RAX: ffffffffffffffda RBX: 00007f23d80210f8 RCX: 00007f23e0013dd7 > [ 3876.800099] RDX: 00007f23d80210f8 RSI: 00000000c020660b RDI: 0000000000000003 > [ 3876.800626] RBP: 000055fa2a2a2440 R08: 0000000000000000 R09: 00007f23ddd96d7c > [ 3876.801143] R10: 00007f23d8022000 R11: 0000000000000246 R12: 00007f23ddd96d80 > [ 3876.801662] R13: 00007f23ddd96d78 R14: 00007f23d80210f0 R15: 00007f23ddd96d80 > (...) > [ 3876.805107] ---[ end trace e53161e179ef04f9 ]--- > > Fix that by saving the root's header owner field into a local variable > before freeing the root's extent buffer, and then use that local variable > when needed. > > Fixes: 30b0463a9394d9 ("Btrfs: fix accessing the root pointer in tree mod log functions") > CC: stable@vger.kernel.org # 3.10+ > Signed-off-by: Filipe Manana <fdmanana@suse.com> Added to 5.3 queue, thanks.
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index 5df76c17775a..0e7ae8da1f95 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -1343,6 +1343,7 @@ get_old_root(struct btrfs_root *root, u64 time_seq) struct tree_mod_elem *tm; struct extent_buffer *eb = NULL; struct extent_buffer *eb_root; + u64 eb_root_owner = 0; struct extent_buffer *old; struct tree_mod_root *old_root = NULL; u64 old_generation = 0; @@ -1380,6 +1381,7 @@ get_old_root(struct btrfs_root *root, u64 time_seq) free_extent_buffer(old); } } else if (old_root) { + eb_root_owner = btrfs_header_owner(eb_root); btrfs_tree_read_unlock(eb_root); free_extent_buffer(eb_root); eb = alloc_dummy_extent_buffer(fs_info, logical); @@ -1396,7 +1398,7 @@ get_old_root(struct btrfs_root *root, u64 time_seq) if (old_root) { btrfs_set_header_bytenr(eb, eb->start); btrfs_set_header_backref_rev(eb, BTRFS_MIXED_BACKREF_REV); - btrfs_set_header_owner(eb, btrfs_header_owner(eb_root)); + btrfs_set_header_owner(eb, eb_root_owner); btrfs_set_header_level(eb, old_root->level); btrfs_set_header_generation(eb, old_generation); }