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From: Phillip Wood <phillip.wood123@gmail.com>
To: phillip.wood@dunelm.org.uk, Junio C Hamano <gitster@pobox.com>,
	Phillip Wood via GitGitGadget <gitgitgadget@gmail.com>
Cc: Derrick Stolee <dstolee@microsoft.com>,
	git@vger.kernel.org,
	Philippe Blain <levraiphilippeblain@gmail.com>,
	Johannes Schindelin <Johannes.Schindelin@gmx.de>,
	Elijah Newren <newren@gmail.com>
Subject: Re: [PATCH 00/11] rebase: reset_head() related fixes and improvements
Date: Sat, 2 Oct 2021 14:12:18 +0100	[thread overview]
Message-ID: <9e5cdff3-a71f-640a-8964-22a7d6b12276@gmail.com> (raw)
In-Reply-To: <ddf5e9c2-3211-cec2-cd18-2a083e279ccb@gmail.com>

On 02/10/2021 13:27, Phillip Wood wrote:
> Hi Junio
> 
> On 02/10/2021 05:58, Junio C Hamano wrote:
>> Junio C Hamano <gitster@pobox.com> writes:
>>
>>> When merged with other topics in flight in 'seen', this seems to
>>> fail the t1092 test (most likely, ds/add-rm-with-sparse-index is
>>> what this interacts badly with).
> 
> Oh dear, thanks for letting me know.
> 
>> There are Two CI runs at GitHub:
>>
>>   - https://github.com/git/git/actions/runs/1297117791 (d3a1c4e)
>>   - https://github.com/git/git/actions/runs/1297232973 (a1108c2)
>>
>> The difference between the former (which passes all the tests) and
>> he latter (which fails) are only two topics:
>>
>>      $ git log --first-parent --oneline d3a1c4e..a1108c2
>>      a1108c2b1b Merge branch 'hn/reftable' into seen
>>      e575f29006 Merge branch 'pw/fix-some-issues-in-reset-head' into seen
>>
>> I think the following is the same failure I saw earlier
>>
>>     
>> https://github.com/git/git/runs/3773780195?check_suite_focus=true#step:6:5033 
>>
>>
>> that the write-tree codepath hits assertion failure by detecting a
>> corruption in the cache-tree data structure.
> 
> The test that fails (t1092-sparse-checkout-compatibility.sh:'merge, 
> cherry-pick, and rebase') was introduced by c0b99303db ("t1092: add 
> cherry-pick, rebase tests", 2021-09-08) and is in v2.33.0. It does not 
> test the "apply" backend of rebase, changing it to do so makes it fail 
> on the current master as that backend already uses reset_head() for the 
> initial checkout so it is an existing bug that is exposed by the changes 
> in this series. It seems to be a use-after-free (see below) I'll try and 
> investigate but I've got no idea what is going on at the moment - the 
> index is not my area of expertise.

removing the call to prime_cache_tree() from reset_head() fixes the 
crash. It is called after unpack_trees() and before 
write_locked_index(), I'm not sure what the implications of removing it 
are - why it was there it is needed?

Best Wishes

Phillip

> Best Wishes
> 
> Phillip
> 
> ==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
>      #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.
>>
> 


  reply	other threads:[~2021-10-02 13:12 UTC|newest]

Thread overview: 85+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-01 10:04 [PATCH 00/11] rebase: reset_head() related fixes and improvements Phillip Wood via GitGitGadget
2021-10-01 10:04 ` [PATCH 01/11] rebase: factor out checkout for up to date branch Phillip Wood via GitGitGadget
2021-10-01 10:04 ` [PATCH 02/11] reset_head(): fix checkout Phillip Wood via GitGitGadget
2021-10-01 20:26   ` Junio C Hamano
2021-10-04  9:58     ` Phillip Wood
2021-10-04 16:13       ` Junio C Hamano
2021-10-01 22:47   ` Eric Sunshine
2021-10-01 10:04 ` [PATCH 03/11] reset_head(): don't run checkout hook if there is an error Phillip Wood via GitGitGadget
2021-10-01 20:52   ` Junio C Hamano
2021-10-04 10:00     ` Phillip Wood
2021-10-12  8:48       ` Ævar Arnfjörð Bjarmason
2021-10-01 10:04 ` [PATCH 04/11] reset_head(): remove action parameter Phillip Wood via GitGitGadget
2021-10-01 20:58   ` Junio C Hamano
2021-10-04 10:00     ` Phillip Wood
2021-10-01 10:04 ` [PATCH 05/11] reset_head(): factor out ref updates Phillip Wood via GitGitGadget
2021-10-01 21:00   ` Junio C Hamano
2021-10-04 10:03     ` Phillip Wood
2021-10-01 10:04 ` [PATCH 06/11] reset_head(): make default_reflog_action optional Phillip Wood via GitGitGadget
2021-10-01 21:03   ` Junio C Hamano
2021-10-01 21:08   ` Junio C Hamano
2021-10-04 10:03     ` Phillip Wood
2021-10-01 10:04 ` [PATCH 07/11] rebase: cleanup reset_head() calls Phillip Wood via GitGitGadget
2021-10-01 10:04 ` [PATCH 08/11] reset_head(): take struct rebase_head_opts Phillip Wood via GitGitGadget
2021-10-01 21:11   ` Junio C Hamano
2021-10-04 10:09     ` Phillip Wood
2021-10-01 10:05 ` [PATCH 09/11] rebase --apply: fix reflog Phillip Wood via GitGitGadget
2021-10-01 21:12   ` Junio C Hamano
2021-10-01 10:05 ` [PATCH 10/11] rebase --apply: set ORIG_HEAD correctly Phillip Wood via GitGitGadget
2021-10-01 21:18   ` Junio C Hamano
2021-10-01 10:05 ` [PATCH 11/11] rebase -m: don't fork git checkout Phillip Wood via GitGitGadget
2021-10-02  0:38 ` [PATCH 00/11] rebase: reset_head() related fixes and improvements Junio C Hamano
2021-10-02  4:58   ` Junio C Hamano
2021-10-02 12:27     ` Phillip Wood
2021-10-02 13:12       ` Phillip Wood [this message]
2021-10-02 13:38       ` René Scharfe
2021-10-06 14:03         ` Phillip Wood
2021-12-08 14:57 ` [PATCH v2 00/14] " Phillip Wood via GitGitGadget
2021-12-08 14:57   ` [PATCH v2 01/14] rebase: factor out checkout for up to date branch Phillip Wood via GitGitGadget
2021-12-09 21:04     ` Junio C Hamano
2021-12-08 14:57   ` [PATCH v2 02/14] t5403: refactor rebase post-checkout hook tests Phillip Wood via GitGitGadget
2021-12-09 18:24     ` Junio C Hamano
2021-12-08 14:57   ` [PATCH v2 03/14] rebase: pass correct arguments to post-checkout hook Phillip Wood via GitGitGadget
2021-12-09 18:53     ` Junio C Hamano
2021-12-08 14:57   ` [PATCH v2 04/14] rebase: do not remove untracked files on checkout Phillip Wood via GitGitGadget
2021-12-09 19:09     ` Junio C Hamano
2021-12-08 14:57   ` [PATCH v2 05/14] rebase --apply: don't run post-checkout hook if there is an error Phillip Wood via GitGitGadget
2021-12-08 14:57   ` [PATCH v2 06/14] reset_head(): remove action parameter Phillip Wood via GitGitGadget
2021-12-08 14:57   ` [PATCH v2 07/14] create_autostash(): remove unneeded parameter Phillip Wood via GitGitGadget
2021-12-09 19:17     ` Junio C Hamano
2022-01-25 11:06       ` Phillip Wood
2021-12-08 14:57   ` [PATCH v2 08/14] reset_head(): factor out ref updates Phillip Wood via GitGitGadget
2021-12-08 14:57   ` [PATCH v2 09/14] reset_head(): make default_reflog_action optional Phillip Wood via GitGitGadget
2021-12-09 19:23     ` Junio C Hamano
2021-12-08 14:57   ` [PATCH v2 10/14] rebase: cleanup reset_head() calls Phillip Wood via GitGitGadget
2021-12-09 19:26     ` Junio C Hamano
2022-01-25 11:07       ` Phillip Wood
2021-12-08 14:57   ` [PATCH v2 11/14] reset_head(): take struct rebase_head_opts Phillip Wood via GitGitGadget
2021-12-09 19:31     ` Junio C Hamano
2021-12-08 14:57   ` [PATCH v2 12/14] rebase --apply: fix reflog Phillip Wood via GitGitGadget
2021-12-09 20:49     ` Junio C Hamano
2021-12-08 14:58   ` [PATCH v2 13/14] rebase --apply: set ORIG_HEAD correctly Phillip Wood via GitGitGadget
2021-12-11 10:59     ` Elijah Newren
2021-12-08 14:58   ` [PATCH v2 14/14] rebase -m: don't fork git checkout Phillip Wood via GitGitGadget
2021-12-09 21:04   ` [PATCH v2 00/14] rebase: reset_head() related fixes and improvements Junio C Hamano
2022-01-26 10:53     ` Phillip Wood
2022-01-27 17:37       ` Junio C Hamano
2021-12-11 11:05   ` Elijah Newren
2022-01-26 13:05   ` [PATCH v3 " Phillip Wood via GitGitGadget
2022-01-26 13:05     ` [PATCH v3 01/14] rebase: factor out checkout for up to date branch Phillip Wood via GitGitGadget
2022-01-26 13:05     ` [PATCH v3 02/14] t5403: refactor rebase post-checkout hook tests Phillip Wood via GitGitGadget
2022-01-26 13:05     ` [PATCH v3 03/14] rebase: pass correct arguments to post-checkout hook Phillip Wood via GitGitGadget
2022-01-26 13:05     ` [PATCH v3 04/14] rebase: do not remove untracked files on checkout Phillip Wood via GitGitGadget
2022-01-26 13:05     ` [PATCH v3 05/14] rebase --apply: don't run post-checkout hook if there is an error Phillip Wood via GitGitGadget
2022-01-26 13:05     ` [PATCH v3 06/14] reset_head(): remove action parameter Phillip Wood via GitGitGadget
2022-01-26 13:05     ` [PATCH v3 07/14] reset_head(): factor out ref updates Phillip Wood via GitGitGadget
2022-01-26 13:05     ` [PATCH v3 08/14] reset_head(): make default_reflog_action optional Phillip Wood via GitGitGadget
2022-01-26 13:05     ` [PATCH v3 09/14] create_autostash(): remove unneeded parameter Phillip Wood via GitGitGadget
2022-01-26 13:05     ` [PATCH v3 10/14] rebase: cleanup reset_head() calls Phillip Wood via GitGitGadget
2022-01-26 13:05     ` [PATCH v3 11/14] reset_head(): take struct rebase_head_opts Phillip Wood via GitGitGadget
2022-01-26 13:35       ` Ævar Arnfjörð Bjarmason
2022-01-26 14:52         ` Phillip Wood
2022-01-26 13:05     ` [PATCH v3 12/14] rebase --apply: fix reflog Phillip Wood via GitGitGadget
2022-01-26 13:05     ` [PATCH v3 13/14] rebase --apply: set ORIG_HEAD correctly Phillip Wood via GitGitGadget
2022-01-26 13:05     ` [PATCH v3 14/14] rebase -m: don't fork git checkout Phillip Wood via GitGitGadget
2022-02-01 17:03     ` [PATCH v3 00/14] rebase: reset_head() related fixes and improvements Elijah Newren

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