fix null pointer dereference

From: =?UTF-8?q?Kleber=20Tarc=C3=ADsio?= <[email protected]>

The malloc function can return null when the memory allocation fails. This commit adds a condition to handle these cases properly. https://cwe.mitre.org/data/definitions/476.html

---
Avoiding null pointer dereference

This pull request aims to fix null pointer dereference.

Null pointer dereference
[https://cwe.mitre.org/data/definitions/476.html]

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-983%2Fklebertarcisio%2Fpatch-1-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-983/klebertarcisio/patch-1-v1
Pull-Request: https://github.com/git/git/pull/983

 builtin/submodule--helper.c | 2 ++
 1 file changed, 2 insertions(+)

index 9d505a6329c8..92349d715a78 100644
@@ -1215,6 +1215,8 @@ static void submodule_summary_callback(struct diff_queue_struct *q,
 		if (!S_ISGITLINK(p->one->mode) && !S_ISGITLINK(p->two->mode))
 			continue;
 		temp = (struct module_cb*)malloc(sizeof(struct module_cb));
+		if (!temp) 
+			die(_("out of memory"));
 		temp->mod_src = p->one->mode;
 		temp->mod_dst = p->two->mode;
 		temp->oid_src = p->one->oid;

base-commit: a5828ae6b52137b913b978e16cd2334482eb4c1f

gitgitgadget

Thanks, from my brief grepping of the remaining code in git.git there is no other malloc() that doesn't have its return value checked appropriately.

Hi, Kleber. And welcome to the list!

If you are going to re-roll this series, please wrap the commit message body at 72 columns. This helps viewing the message in 80-columns terminals. (For more info on this and other commit message conventions used by the Git project, please take a look at the corresponding sections at Documentation/MyFirstContribution.txt and Documentation/SubmittingPatches).

Thanks,
Matheus

Thanks, but see Documentation/SubmittingPatches for general guidelines. Our commit title begins with "<area>:" so that when this change is buried among hundreds of other commits in "git shortlog --no-merges", the readers can tell what it is about.

Subject: [PATCH] submodule-helper: avoid unchecked malloc()

perhaps.

Overlong line. Also when you can say something without forcing readers to refer to external material, do so (and if you do not think you can, try harder ;-).

In this case, I think you do not need to say
anything more than

submodule-helper.c::submodule_summary_callback() calls malloc() and uses the returned value without checking for NULLness. Use xmalloc() instaed.