fix for a simple typo #9
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josefbacik
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Jan 9, 2020
…_info_cache()
This bug is exposed by fsck-test with D=asan, hit by test case 020, with
the following error report:
=================================================================
==10740==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x621000061580 at pc 0x56051f0db6cd bp 0x7ffe170f3e20 sp 0x7ffe170f3e10
READ of size 1 at 0x621000061580 thread T0
#0 0x56051f0db6cc in btrfs_extent_inline_ref_type /home/adam/btrfs/btrfs-progs/ctree.h:1727
#1 0x56051f13b669 in build_roots_info_cache /home/adam/btrfs/btrfs-progs/cmds-check.c:14306
#2 0x56051f13c86a in repair_root_items /home/adam/btrfs/btrfs-progs/cmds-check.c:14450
#3 0x56051f13ea89 in cmd_check /home/adam/btrfs/btrfs-progs/cmds-check.c:14965
#4 0x56051efe75bb in main /home/adam/btrfs/btrfs-progs/btrfs.c:302
#5 0x7f04ddbb0f49 in __libc_start_main (/usr/lib/libc.so.6+0x20f49)
#6 0x56051efe68c9 in _start (/home/adam/btrfs/btrfs-progs/btrfs+0x5b8c9)
0x621000061580 is located 0 bytes to the right of 4224-byte region [0x621000060500,0x621000061580)
allocated by thread T0 here:
#0 0x7f04ded50ce1 in __interceptor_calloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cc:70
#1 0x56051f04685e in __alloc_extent_buffer /home/adam/btrfs/btrfs-progs/extent_io.c:553
#2 0x56051f047563 in alloc_extent_buffer /home/adam/btrfs/btrfs-progs/extent_io.c:687
#3 0x56051efff1d1 in btrfs_find_create_tree_block /home/adam/btrfs/btrfs-progs/disk-io.c:187
#4 0x56051f000133 in read_tree_block /home/adam/btrfs/btrfs-progs/disk-io.c:327
#5 0x56051efeddb8 in read_node_slot /home/adam/btrfs/btrfs-progs/ctree.c:652
#6 0x56051effb0d9 in btrfs_next_leaf /home/adam/btrfs/btrfs-progs/ctree.c:2853
#7 0x56051f13b343 in build_roots_info_cache /home/adam/btrfs/btrfs-progs/cmds-check.c:14267
#8 0x56051f13c86a in repair_root_items /home/adam/btrfs/btrfs-progs/cmds-check.c:14450
#9 0x56051f13ea89 in cmd_check /home/adam/btrfs/btrfs-progs/cmds-check.c:14965
#10 0x56051efe75bb in main /home/adam/btrfs/btrfs-progs/btrfs.c:302
#11 0x7f04ddbb0f49 in __libc_start_main (/usr/lib/libc.so.6+0x20f49)
It's completely possible that one extent/metadata item has no inline
reference, while build_roots_info_cache() doesn't have such check.
Fix it by checking @iref against item end to avoid such problem.
Issue: #92
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
josefbacik
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Jan 9, 2020
…y wrong condition to free delayed ref/head.
[BUG]
When btrfs-progs is compiled with D=asan, it can't pass even the very
basic fsck tests due to btrfs-image has memory leak:
=== START TEST /home/adam/btrfs/btrfs-progs/tests//fsck-tests/001-bad-file-extent-bytenr
restoring image default_case.img
=================================================================
==7790==ERROR: LeakSanitizer: detected memory leaks
Direct leak of 104 byte(s) in 1 object(s) allocated from:
#0 0x7f1d3b738389 in __interceptor_malloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cc:86
#1 0x560ca6b7f4ff in btrfs_add_delayed_tree_ref /home/adam/btrfs/btrfs-progs/delayed-ref.c:569
#2 0x560ca6af2d0b in btrfs_free_extent /home/adam/btrfs/btrfs-progs/extent-tree.c:2155
#3 0x560ca6ac16ca in __btrfs_cow_block /home/adam/btrfs/btrfs-progs/ctree.c:319
#4 0x560ca6ac1d8c in btrfs_cow_block /home/adam/btrfs/btrfs-progs/ctree.c:383
#5 0x560ca6ac6c8e in btrfs_search_slot /home/adam/btrfs/btrfs-progs/ctree.c:1153
#6 0x560ca6ab7e83 in fixup_device_size image/main.c:2113
#7 0x560ca6ab9279 in fixup_chunks_and_devices image/main.c:2333
#8 0x560ca6ab9ada in restore_metadump image/main.c:2455
#9 0x560ca6abaeba in main image/main.c:2723
#10 0x7f1d3b148ce2 in __libc_start_main (/usr/lib/libc.so.6+0x23ce2)
... tons of similar leakage for delayed_tree_ref ...
Direct leak of 96 byte(s) in 1 object(s) allocated from:
#0 0x7f1d3b738389 in __interceptor_malloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cc:86
#1 0x560ca6b7f5fb in btrfs_add_delayed_tree_ref /home/adam/btrfs/btrfs-progs/delayed-ref.c:583
#2 0x560ca6af5679 in alloc_tree_block /home/adam/btrfs/btrfs-progs/extent-tree.c:2503
#3 0x560ca6af57ac in btrfs_alloc_free_block /home/adam/btrfs/btrfs-progs/extent-tree.c:2524
#4 0x560ca6ac115b in __btrfs_cow_block /home/adam/btrfs/btrfs-progs/ctree.c:290
#5 0x560ca6ac1d8c in btrfs_cow_block /home/adam/btrfs/btrfs-progs/ctree.c:383
#6 0x560ca6b7bb15 in commit_tree_roots /home/adam/btrfs/btrfs-progs/transaction.c:98
#7 0x560ca6b7c525 in btrfs_commit_transaction /home/adam/btrfs/btrfs-progs/transaction.c:192
#8 0x560ca6ab92be in fixup_chunks_and_devices image/main.c:2337
#9 0x560ca6ab9ada in restore_metadump image/main.c:2455
#10 0x560ca6abaeba in main image/main.c:2723
#11 0x7f1d3b148ce2 in __libc_start_main (/usr/lib/libc.so.6+0x23ce2)
... tons of similar leakage for delayed_ref_head ...
SUMMARY: AddressSanitizer: 1600 byte(s) leaked in 16 allocation(s).
failed to restore image ./default_case.img
[CAUSE]
Commit c603970 ("btrfs-progs: Add delayed refs infrastructure")
introduces delayed ref infrastructure for free space tree, however the
refcount_dec_and_test() from kernel code is wrongly backported.
refcount_dec_and_test() will return true if the refcount reaches 0.
So kernel code will free the allocated space as expected:
if (refcount_dec_and_test(&ref->refs)) {
kmem_cache_free();
}
However btrfs-progs backport is using the opposite condition:
if (--ref->refs) {
kfree();
}
This will not free the memory for the last user, but for refs >= 2.
Causing both use-after-free and memory leak for any offline write
operation.
[FIX]
Fix the (--ref->refs) condition to (--ref->refs == 0) to fix the
backport error.
Fixes: c603970 ("btrfs-progs: Add delayed refs infrastructure")
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
josefbacik
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Feb 16, 2021
Pull-request: #9 Signed-off-by: David Sterba <dsterba@suse.com>
josefbacik
pushed a commit
that referenced
this pull request
Feb 22, 2022
…level
[BUG]
When running lowmem mode with METADATA_ITEM which has invalid level, it
will crash with the following backtrace:
(gdb) bt
#0 0x0000555555616b0b in btrfs_header_bytenr (eb=0x4)
at ./kernel-shared/ctree.h:2134
#1 0x0000555555620c78 in check_tree_block_backref (root_id=5,
bytenr=30457856, level=256) at check/mode-lowmem.c:3818
#2 0x0000555555621f6c in check_extent_item (path=0x7fffffffd9c0)
at check/mode-lowmem.c:4334
#3 0x00005555556235a5 in check_leaf_items (root=0x555555688e10,
path=0x7fffffffd9c0, nrefs=0x7fffffffda30, account_bytes=1)
at check/mode-lowmem.c:4835
#4 0x0000555555623c6d in walk_down_tree (root=0x555555688e10,
path=0x7fffffffd9c0, level=0x7fffffffd984, nrefs=0x7fffffffda30,
check_all=1) at check/mode-lowmem.c:4967
#5 0x000055555562494f in check_btrfs_root (root=0x555555688e10, check_all=1)
at check/mode-lowmem.c:5266
#6 0x00005555556254ee in check_chunks_and_extents_lowmem ()
at check/mode-lowmem.c:5556
#7 0x00005555555f0b82 in do_check_chunks_and_extents () at check/main.c:9114
#8 0x00005555555f50ea in cmd_check (cmd=0x55555567c640 <cmd_struct_check>,
argc=3, argv=0x7fffffffdec0) at check/main.c:10892
#9 0x000055555556b2b1 in cmd_execute (argv=0x7fffffffdec0, argc=3,
cmd=0x55555567c640 <cmd_struct_check>) at cmds/commands.h:125
[CAUSE]
For function check_extent_item() it will go through inline extent items
and then check their backrefs.
But for METADATA_ITEM, it doesn't really validate key.offset, which is
u64 and can contain value way larger than BTRFS_MAX_LEVEL (mostly caused
by bit flip).
In that case, if we have a larger value like 256 in key.offset, then
later check_tree_block_backref() will use 256 as level, and overflow
path->nodes[level] and crash.
[FIX]
Just verify the level, no matter if it's from btrfs_tree_block_level()
(which is just u8), or it's from key.offset (which is u64).
To do the check properly and detect higher bits corruption, also change
the type of @Level from u8 to u64.
Now lowmem mode can detect the problem properly:
...
[2/7] checking extents
ERROR: tree block 30457856 has bad backref level, has 256 expect [0, 7]
ERROR: extent[30457856 16384] level mismatch, wanted: 0, have: 256
ERROR: errors found in extent allocation tree or chunk allocation
[3/7] checking free space tree
...
Reviewed-by: Su Yue <l@damenly.su>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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