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mv: handle lstat() failure correctly

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When moving a directory onto another with `git mv` various checks are
performed. One of of these validates that the destination is not existing.

When calling `lstat` on the destination path and it fails as the path
doesn't exist, some environments seem to overwrite the passed  in
`stat` memory nonetheless (I observed this issue on debian 12 of x86_64,
running on OrbStack on ARM, emulated with Rosetta).

This would affect the code that followed as it would still acccess a now
modified `st` structure, which now seems to contain uninitialized memory.
`S_ISDIR(st_dir_mode)` would then typically return false causing the code
to run into a bad case.

The fix avoids overwriting the existing `st` structure, providing an
alternative that exists only for that purpose.

Note that this patch minimizes complexity instead of stack-frame size.

Signed-off-by: Sebastian Thiel <sebastian.thiel@icloud.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Sebastian Thiel 2023-08-09 07:47:41 +00:00 committed by Junio C Hamano
parent fb7d80edca
commit 72695d8214
2 changed files with 9 additions and 2 deletions
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4
builtin/mv.c
View file

@ -183,7 +183,7 @@ int cmd_mv(int argc, const char **argv, const char *prefix)
int src_dir_nr = 0, src_dir_alloc = 0;
struct strbuf a_src_dir = STRBUF_INIT;
enum update_mode *modes, dst_mode = 0;
struct stat st;
struct stat st, dest_st;
struct string_list src_for_dst = STRING_LIST_INIT_NODUP;
struct lock_file lock_file = LOCK_INIT;
struct cache_entry *ce;
@ -303,7 +303,7 @@ int cmd_mv(int argc, const char **argv, const char *prefix)
goto act_on_entry;
}
if (S_ISDIR(st.st_mode)
&& lstat(dst, &st) == 0) {
&& lstat(dst, &dest_st) == 0) {
bad = _("cannot move directory over file");
goto act_on_entry;
}

7
t/t7001-mv.sh
View file

@ -174,6 +174,13 @@ test_expect_success 'do not move directory over existing directory' '
test_must_fail git mv path2 path0
'
test_expect_success 'rename directory to non-existing directory' '
mkdir dir-a &&
>dir-a/f &&
git add dir-a &&
git mv dir-a non-existing-dir
'
test_expect_success 'move into "."' '
git mv path1/path2/ .
'