git pull --rebase on a corrupted HEAD used to segfault; it has been
corrected to error out with a message. A test has also been added to
verify this fix.
Signed-off-by: André Laszlo <andre@xxxxxxxxx>
---
Notes:
When add_head_to_pending fails to add a pending object, git pull
--rebase segfaults. This can happen if HEAD is referring to a corrupt
or missing object.
I discovered this segfault on my machine after pulling a repo from
GitHub, but I have been unable to reproduce the sequence of events
that lead to the corrupted HEAD (I think it may have been caused by a
lost network connection in my case).
The following commands use add_head_to_pending:
format-patch setup_revisions before add_head_to_pending
diff checks rev.pending.nr
shortlog checks rev.pending.nr
log uses resolve_ref_unsafe
All of the above return an error code of 128 and print "fatal: bad
object HEAD" instead of segfaulting, which I think is correct
behavior. The check and error message have been added to
has_uncommitted_changes, where they were missing, as well as to
diff-lib.c (without the error message).
diff-lib.c | 2 +-
t/t5520-pull.sh | 12 ++++++++++++
wt-status.c | 5 +++++
3 files changed, 18 insertions(+), 1 deletion(-)
diff --git a/diff-lib.c b/diff-lib.c
index 52447466b..9d26b18c3 100644
--- a/diff-lib.c
+++ b/diff-lib.c
@@ -512,7 +512,7 @@ int run_diff_index(struct rev_info *revs, int cached)
struct object_array_entry *ent;
ent = revs->pending.objects;
- if (diff_cache(revs, ent->item->oid.hash, ent->name, cached))
+ if (!ent || diff_cache(revs, ent->item->oid.hash, ent->name, cached))
exit(128);
diff_set_mnemonic_prefix(&revs->diffopt, "c/", cached ? "i/" : "w/");
diff --git a/t/t5520-pull.sh b/t/t5520-pull.sh
index 17f4d0fe4..1edb6a97a 100755
--- a/t/t5520-pull.sh
+++ b/t/t5520-pull.sh
@@ -664,4 +664,16 @@ test_expect_success 'git pull --rebase against local branch' '
test file = "$(cat file2)"
'
+test_expect_success 'git pull --rebase with corrupt HEAD does not segfault' '
+ mkdir corrupted &&
+ (cd corrupted &&
+ git init &&
+ echo one >file && git add file &&
+ git commit -m one &&
+ REV=$(git rev-parse HEAD) &&
+ rm -f .git/objects/${REV:0:2}/${REV:2} &&
+ test_expect_code 128 git pull --rebase > /dev/null
+ )
+'
+
test_done
diff --git a/wt-status.c b/wt-status.c
index d47012048..3d60eaff5 100644
--- a/wt-status.c
+++ b/wt-status.c
@@ -2252,6 +2252,11 @@ int has_uncommitted_changes(int ignore_submodules)
DIFF_OPT_SET(&rev_info.diffopt, IGNORE_SUBMODULES);
DIFF_OPT_SET(&rev_info.diffopt, QUICK);
add_head_to_pending(&rev_info);
+
+ /* The add_head_to_pending call might not have added anything. */
+ if (!rev_info.pending.nr)
+ die("bad object %s", "HEAD");
+
diff_setup_done(&rev_info.diffopt);
result = run_diff_index(&rev_info, 1);
return diff_result_code(&rev_info.diffopt, result);
--
2.12.0