Re: [PATCH 00/11] rebase: reset_head() related fixes and improvements
Hi René
On 02/10/2021 14:38, René Scharfe wrote:
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>[..]
>> ==74345==ERROR: AddressSanitizer: heap-use-after-free on address 0x606000001b20 at pc 0x557cbe82d3a2 bp 0x7ffdfee08090 sp 0x7ffdfee08080
>> READ of size 4 at 0x606000001b20 thread T0
>> #0 0x557cbe82d3a1 in verify_one /home/phil/src/git/cache-tree.c:863
>> #1 0x557cbe82ca9d in verify_one /home/phil/src/git/cache-tree.c:840
>> #2 0x557cbe82ca9d in verify_one /home/phil/src/git/cache-tree.c:840
>> #3 0x557cbe82ca9d in verify_one /home/phil/src/git/cache-tree.c:840
>> #4 0x557cbe830a2b in cache_tree_verify /home/phil/src/git/cache-tree.c:910
>> #5 0x557cbea53741 in write_locked_index /home/phil/src/git/read-cache.c:3250
>> #6 0x557cbeab7fdd in reset_head /home/phil/src/git/reset.c:87
>> #7 0x557cbe72147f in cmd_rebase builtin/rebase.c:2074
>> #8 0x557cbe5bd151 in run_builtin /home/phil/src/git/git.c:461
>> #9 0x557cbe5bd151 in handle_builtin /home/phil/src/git/git.c:714
>> #10 0x557cbe5c0503 in run_argv /home/phil/src/git/git.c:781
>> #11 0x557cbe5c0503 in cmd_main /home/phil/src/git/git.c:912
>> #12 0x557cbe5bad28 in main /home/phil/src/git/common-main.c:52
>> #13 0x7fdd4b82eb24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)
>> #14 0x557cbe5bcb8d in _start (/home/phil/src/git/git+0x1b9b8d)
>>
>> 0x606000001b20 is located 0 bytes inside of 56-byte region [0x606000001b20,0x606000001b58)
>> freed by thread T0 here:
>> #0 0x7fdd4bacff19 in __interceptor_free /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cpp:127
>> #1 0x557cbe82af60 in cache_tree_free /home/phil/src/git/cache-tree.c:35
>> #2 0x557cbe82aee5 in cache_tree_free /home/phil/src/git/cache-tree.c:31
>> #3 0x557cbe82aee5 in cache_tree_free /home/phil/src/git/cache-tree.c:31
>> #4 0x557cbe82aee5 in cache_tree_free /home/phil/src/git/cache-tree.c:31
>> #5 0x557cbeb2557a in ensure_full_index /home/phil/src/git/sparse-index.c:310
>> #6 0x557cbea45c4a in index_name_stage_pos /home/phil/src/git/read-cache.c:588
>> #7 0x557cbe82ce37 in verify_one /home/phil/src/git/cache-tree.c:850
>> #8 0x557cbe82ca9d in verify_one /home/phil/src/git/cache-tree.c:840
>> #9 0x557cbe82ca9d in verify_one /home/phil/src/git/cache-tree.c:840
>> #10 0x557cbe82ca9d in verify_one /home/phil/src/git/cache-tree.c:840
>> #11 0x557cbe830a2b in cache_tree_verify /home/phil/src/git/cache-tree.c:910
>
> Looks like cache_tree_verify() indirectly triggered ensure_full_index(),
> which throws the cache_tree away, then kept going using stale pointers.
> It should instead stop and start over in such a case, no?
Thanks for that, I found it really helpful
Best Wishes
Phillip
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>> #12 0x557cbea53741 in write_locked_index /home/phil/src/git/read-cache.c:3250
>> #13 0x557cbeab7fdd in reset_head /home/phil/src/git/reset.c:87
>> #14 0x557cbe72147f in cmd_rebase builtin/rebase.c:2074
>> #15 0x557cbe5bd151 in run_builtin /home/phil/src/git/git.c:461
>> #16 0x557cbe5bd151 in handle_builtin /home/phil/src/git/git.c:714
>> #17 0x557cbe5c0503 in run_argv /home/phil/src/git/git.c:781
>> #18 0x557cbe5c0503 in cmd_main /home/phil/src/git/git.c:912
>> #19 0x557cbe5bad28 in main /home/phil/src/git/common-main.c:52
>> #20 0x7fdd4b82eb24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)
>>
>> previously allocated by thread T0 here:
>> #0 0x7fdd4bad0459 in __interceptor_calloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cpp:154
>> #1 0x557cbebc1807 in xcalloc /home/phil/src/git/wrapper.c:140
>> #2 0x557cbe82b7d8 in cache_tree /home/phil/src/git/cache-tree.c:17
>> #3 0x557cbe82b7d8 in prime_cache_tree_rec /home/phil/src/git/cache-tree.c:763
>> #4 0x557cbe82b837 in prime_cache_tree_rec /home/phil/src/git/cache-tree.c:764
>> #5 0x557cbe82b837 in prime_cache_tree_rec /home/phil/src/git/cache-tree.c:764
>> #6 0x557cbe8304e1 in prime_cache_tree /home/phil/src/git/cache-tree.c:779
>> #7 0x557cbeab7fa7 in reset_head /home/phil/src/git/reset.c:85
>> #8 0x557cbe72147f in cmd_rebase builtin/rebase.c:2074
>> #9 0x557cbe5bd151 in run_builtin /home/phil/src/git/git.c:461
>> #10 0x557cbe5bd151 in handle_builtin /home/phil/src/git/git.c:714
>> #11 0x557cbe5c0503 in run_argv /home/phil/src/git/git.c:781
>> #12 0x557cbe5c0503 in cmd_main /home/phil/src/git/git.c:912
>> #13 0x557cbe5bad28 in main /home/phil/src/git/common-main.c:52
>> #14 0x7fdd4b82eb24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)
>>
>> SUMMARY: AddressSanitizer: heap-use-after-free /home/phil/src/git/cache-tree.c:863 in verify_one
>> Shadow bytes around the buggy address:
>> 0x0c0c7fff8310: fd fd fd fd fd fd fd fa fa fa fa fa fd fd fd fd
>> 0x0c0c7fff8320: fd fd fd fa fa fa fa fa fd fd fd fd fd fd fd fa
>> 0x0c0c7fff8330: fa fa fa fa 00 00 00 00 00 00 00 02 fa fa fa fa
>> 0x0c0c7fff8340: fd fd fd fd fd fd fd fa fa fa fa fa 00 00 00 00
>> 0x0c0c7fff8350: 00 00 00 02 fa fa fa fa fd fd fd fd fd fd fd fa
>> =>0x0c0c7fff8360: fa fa fa fa[fd]fd fd fd fd fd fd fa fa fa fa fa
>> 0x0c0c7fff8370: 00 00 00 00 00 00 00 02 fa fa fa fa fd fd fd fd
>> 0x0c0c7fff8380: fd fd fd fa fa fa fa fa 00 00 00 00 00 00 00 02
>> 0x0c0c7fff8390: fa fa fa fa fd fd fd fd fd fd fd fa fa fa fa fa
>> 0x0c0c7fff83a0: fd fd fd fd fd fd fd fa fa fa fa fa fd fd fd fd
>> 0x0c0c7fff83b0: fd fd fd fa fa fa fa fa 00 00 00 00 00 00 00 fa
>> Shadow byte legend (one shadow byte represents 8 application bytes):
>> Addressable: 00
>> Partially addressable: 01 02 03 04 05 06 07
>> Heap left redzone: fa
>> Freed heap region: fd
>> Stack left redzone: f1
>> Stack mid redzone: f2
>> Stack right redzone: f3
>> Stack after return: f5
>> Stack use after scope: f8
>> Global redzone: f9
>> Global init order: f6
>> Poisoned by user: f7
>> Container overflow: fc
>> Array cookie: ac
>> Intra object redzone: bb
>> ASan internal: fe
>> Left alloca redzone: ca
>> Right alloca redzone: cb
>> Shadow gap: cc
>> ==74345==ABORTING
>>
>>
>>> e575f29006 (i.e. without the reftable topic) fails t1092. If you
>>> revert e575f29006^2 (i.e. the "do not fork 'git checkout'") from
>>> that merge, all tests pass including t1092.
>>>
>>> The reftable topic is queued near the tip of 'seen' not necessarily
>>> because it _breaks_ CI (I do not think it does), but it needed a
>>> handful of fixup commits on top. The topic needs rerolling with the
>>> fixes squashed in.
>>>
>>> Thanks.
>>>
>>
>