Skip to contentSkip to conversation

Fix memory leak in function handle_content_type

PATCH In review Alex via GitGitGadget 5 participants 8 messages Jun 13, 2025 – Jun 16, 2025

lore
Share & tools
lore

Alex via GitGitGadget

author
#0 lore raw

PATCH 1/1 Fix memory leak in function handle_content_type

From: jinyaoguo <[email protected]>

The function handle_content_type allocates memory for boundary using xmalloc(sizeof(struct strbuf)). If (++mi->content_top >= &mi->content[MAX_BOUNDARIES]) is true, the function returns without freeing boundary.

Signed-off-by Alex Guo <[email protected]>

---
Fix memory leak in function handle_content_type

The function handle_content_type allocates memory for boundary using xmalloc(sizeof(struct strbuf)). If (++mi->content_top >= &mi->content[MAX_BOUNDARIES]) is true, the function returns without freeing boundary.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-1997%2Fmugitya03%2Fmlk-2-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-1997/mugitya03/mlk-2-v1
Pull-Request: https://github.com/git/git/pull/1997

 mailinfo.c | 3 +++
 1 file changed, 3 insertions(+)
mailinfo.c +3 -0
index ee4597da6be..e0ea358311f 100644
@@ -266,6 +266,9 @@ static void handle_content_type(struct mailinfo *mi, struct strbuf *line)
 			error("Too many boundaries to handle");
 			mi->input_error = -1;
 			mi->content_top = &mi->content[MAX_BOUNDARIES] - 1;
+			strbuf_release(boundary);
+			free(boundary);
+			boundary = NULL;
 			return;
 		}
 		*(mi->content_top) = boundary;

base-commit: 9edff09aec9b5aaa3d5528129bb279a4d34cf5b3

Signature · 1 line
gitgitgadget
#2 lore raw

Hi Kristoffer,

Sorry for that. I’m still getting familiar with the Git patch submission workflow and missed the sign-off requirement. I believe the confusion came from using two different Git identities. I’ve now added individual “Signed-off-by” lines for both accounts.

From b39b1a8176a344a2fa2c46a6d0ffc27a7bfd9edd Mon Sep 17 00:00:00 2001
From: jinyaoguo <[email protected]>
Date: Thu, 12 Jun 2025 18:48:24 -0400
Subject: [PATCH] Fix memory leak in function handle_content_type

The function handle_content_type allocates memory for boundary using xmalloc(sizeof(struct strbuf)). If (++mi->content_top >= &mi->content[MAX_BOUNDARIES]) is true, the function returns without freeing boundary.

Signed-off-by Alex Guo <[email protected]>
Signed-off-by jinyaoguo <[email protected]>
---
 mailinfo.c | 3 +++
 1 file changed, 3 insertions(+)
mailinfo.c +3 -0
index ee4597da6b..e0ea358311 100644
@@ -266,6 +266,9 @@ static void handle_content_type(struct mailinfo *mi, struct strbuf *line)
                        error("Too many boundaries to handle");
                        mi->input_error = -1;
                        mi->content_top = &mi->content[MAX_BOUNDARIES] - 1;
+                       strbuf_release(boundary);
+                       free(boundary);
+                       boundary = NULL;
                        return;
                }
                *(mi->content_top) = boundary;

--
2.34.1

________________________________________
From: Kristoffer Haugsbakk <[email protected]>
Sent: Friday, June 13, 2025 12:59
To: Josh Soref <[email protected]>; [email protected] <[email protected]>
Cc: Alex <[email protected]>; Jinyao Guo <[email protected]>
Subject: Re: [PATCH] Fix memory leak in function handle_content_type

[You don't often get email from [email protected]. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]

---- External Email: Use caution with attachments, links, or sharing data ----

Quoted 5 lines · Alex via GitGitGadget

From: jinyaoguo <[email protected]>

[snip]

Signed-off-by Alex Guo <[email protected]>

Like what was said on another patch[1] the From and Signed-off-by names need to match. I didn’t see a resolution to that?

If forwarding you need to add your signoff after theirs.

[1]: https://lore.kernel.org/git/[email protected]/

--
Kristoffer Haugsbakk

#3 lore raw
Quoted 3 lines · Jinyao Guo

... I believe
the confusion came from using two different Git identities. I’ve now added individual “Signed-off-by” lines for both accounts.

Please do not do this, if these two are the same single person.

Instead, pick the one you want to be known as to this community, and use that consistently while working on this project.

Thanks.

#4 lore raw

Sure. I'll choose one account and use it consistently.

Here is the edited patch:

From 04b286cb2e736c3a53287b6ddf406e704f19fb2e Mon Sep 17 00:00:00 2001
From: jinyaoguo <[email protected]>
Date: Thu, 12 Jun 2025 18:48:24 -0400
Subject: [PATCH] Fix memory leak in function handle_content_type

The function handle_content_type allocates memory for boundary using xmalloc(sizeof(struct strbuf)). If (++mi->content_top >= &mi->content[MAX_BOUNDARIES]) is true, the function returns without freeing boundary.

Signed-off-by jinyaoguo <[email protected]>
---
 mailinfo.c | 3 +++
 1 file changed, 3 insertions(+)
mailinfo.c +3 -0
index ee4597da6b..e0ea358311 100644
@@ -266,6 +266,9 @@ static void handle_content_type(struct mailinfo *mi, struct strbuf *line)
 			error("Too many boundaries to handle");
 			mi->input_error = -1;
 			mi->content_top = &mi->content[MAX_BOUNDARIES] - 1;
+			strbuf_release(boundary);
+			free(boundary);
+			boundary = NULL;
 			return;
 		}
 		*(mi->content_top) = boundary;
Signature · 13 lines
2.34.1 


Best,
Jinyao
________________________________________
From: Junio C Hamano <[email protected]>
Sent: Friday, June 13, 2025 15:06
To: Jinyao Guo <[email protected]>
Cc: Kristoffer Haugsbakk <[email protected]>; Josh Soref <[email protected]>; [email protected] <[email protected]>; Alex <[email protected]>
Subject: Re: [PATCH] Fix memory leak in function handle_content_type
 
---- External Email: Use caution with attachments, links, or sharing data ----
Quoted 3 lines · Jinyao Guo

... I believe
the confusion came from using two different Git identities.  I’ve now added individual “Signed-off-by” lines for both accounts.

Please do not do this, if these two are the same single person.

Instead, pick the one you want to be known as to this community, and use that consistently while working on this project.

Thanks.

#5 lore raw

mailinfo.c static void handle_content_type(struct mailinfo *mi, struct strbuf *line) · line 274

Quoted 10 lines · Jinyao Guo
mailinfo.c +3 -0
@@ -266,6 +266,9 @@ static void handle_content_type(struct mailinfo *mi, struct strbuf *line)
 			error("Too many boundaries to handle");
 			mi->input_error = -1;
 			mi->content_top = &mi->content[MAX_BOUNDARIES] - 1;
+			strbuf_release(boundary);
+			free(boundary);
+			boundary = NULL;
 			return;
 		}
 		*(mi->content_top) = boundary;

"boundary" is a on-stack local variable. There is no need to assign NULL to it immediately before you return. In the post-context of this hunk, we free it but leave the variable pointing at a random place after that before returning.

#6 lore raw
In reply to Jinyao Guo

Jinyao Guo <[email protected]> writes：

Quoted 36 lines

Sure. I'll choose one account and use it consistently.

Here is the edited patch:

From 04b286cb2e736c3a53287b6ddf406e704f19fb2e Mon Sep 17 00:00:00 2001
From: jinyaoguo <[email protected]>
Date: Thu, 12 Jun 2025 18:48:24 -0400
Subject: [PATCH] Fix memory leak in function handle_content_type

The function handle_content_type allocates memory for boundary using xmalloc(sizeof(struct strbuf)). If (++mi->content_top >= &mi->content[MAX_BOUNDARIES]) is true, the function returns without freeing boundary.

Signed-off-by jinyaoguo <[email protected]>

---
mailinfo.c | 3 +++

1 file changed, 3 insertions(+)
mailinfo.c +3 -0
index ee4597da6b..e0ea358311 100644
@@ -266,6 +266,9 @@ static void handle_content_type(struct mailinfo *mi, struct strbuf *line)
 error("Too many boundaries to handle");
 mi->input_error = -1;
 mi->content_top = &mi->content[MAX_BOUNDARIES] - 1;
+ strbuf_release(boundary);
+ free(boundary);
+ boundary = NULL;
 return;
 }
 *(mi->content_top) = boundary;
Signature · 1 line
2.34.1

May be using goto here would be better. Like:

---

mailinfo.c +2 -1
index ee4597da6b..83358b7517 100644
@@ -266,13 +266,14 @@ static void handle_content_type(struct mailinfo *mi, struct strbuf *line)
                        error("Too many boundaries to handle");
                        mi->input_error = -1;
                        mi->content_top = &mi->content[MAX_BOUNDARIES] - 1;
-                       return;
+                       goto out;
                }
                *(mi->content_top) = boundary;
                boundary = NULL;
        }
        slurp_attr(line->buf, "charset=", &mi->charset);
 
+out:
        if (boundary) {
                strbuf_release(boundary);
                free(boundary);

—

Lidong

#7 lore raw
Quoted 1 line · Lidong Yan

Subject: Re: [PATCH] Fix memory leak in function handle_content_type

The subject should probably be something like

Subject: [PATCH] mailinfo.c: plug memory leak in handle_content_type()

Quoted 23 lines

May be using goto here would be better. Like:

---

mailinfo.c +2 -1
index ee4597da6b..83358b7517 100644
@@ -266,13 +266,14 @@ static void handle_content_type(struct mailinfo *mi, struct strbuf *line)
                        error("Too many boundaries to handle");
                        mi->input_error = -1;
                        mi->content_top = &mi->content[MAX_BOUNDARIES] - 1;
-                       return;
+                       goto out;
                }
                *(mi->content_top) = boundary;
                boundary = NULL;
        }
        slurp_attr(line->buf, "charset=", &mi->charset);
 
+out:
        if (boundary) {
                strbuf_release(boundary);
                free(boundary);
Quoted 1 line

—

Yup, that one looks good enough.

If we wanted to clean up this code path even further, I think the first clean-up to do is to reconsider the use of "struct strbuf *" (instead of "const char *") in *(mi->content_top). strbuf is a fine and less error-prone mechanism to use while you have to manipulate character strings (like parsing from input line to formulate the boundary string), but once this function computed what was asked by the caller, the computed result (like the boundary string) almost always do not need to be editable. But such a code improvement is totally outside the topic of this patch.