threads / patch / 14995

patchAllow emails with boundaries to work again

Subject: [PATCH] Allow emails with boundaries to work again

## tl;dr

5 messages between Aug 13, 2008 and Aug 14, 2008. Diffs are folded; open one to read it.

replies: 4people: 2as markdown or json

Don Zickus· Aug 13, 2008, 22:45 UTC · lore

Recent changes to is_multipart_boundary() caused git-mailinfo to segfault. The reason was after handling the end of the boundary the code tried to look for another boundary. Because the boundary list was empty, dereferencing the pointer to the top of the boundary caused the program to go boom.

The fix is to check to see if the list is empty and if so go on its merry way instead of looking for another boundary.

I also fixed a couple of increments and decrements that didn't look correct relating to content_top.

Signed-Off-by: Don Zickus <dzickus@redhat.com>
---
 builtin-mailinfo.c |   12 +++++++-----
 1 files changed, 7 insertions(+), 5 deletions(-)

Show changes to builtin-mailinfo.c +7 −5

diff --git a/builtin-mailinfo.c b/builtin-mailinfo.c
index 6ae2bf3..0209e82 100644
--- a/builtin-mailinfo.c
+++ b/builtin-mailinfo.c
@@ -175,7 +175,7 @@ static void handle_content_type(struct strbuf *line)
 		 message_type = TYPE_OTHER;
 	if (slurp_attr(line->buf, "boundary=", boundary)) {
 		strbuf_insert(boundary, 0, "--", 2);
-		if (content_top++ >= &content[MAX_BOUNDARIES]) {
+		if (++content_top > &content[MAX_BOUNDARIES]) {
 			fprintf(stderr, "Too many boundaries to handle\n");
 			exit(1);
 		}
@@ -626,7 +626,7 @@ again:
 		/* technically won't happen as is_multipart_boundary()
 		   will fail first.  But just in case..
 		 */
-		if (content_top-- < content) {
+		if (--content_top < content) {
 			fprintf(stderr, "Detected mismatched boundaries, "
 					"can't recover\n");
 			exit(1);
@@ -635,9 +635,11 @@ again:
 		strbuf_release(&newline);
 
 		/* skip to the next boundary */
-		if (!find_boundary())
-			return 0;
-		goto again;
+		if (*content_top) {
+			if (!find_boundary())
+				return 0;
+			goto again;
+		}
 	}
 
 	/* set some defaults */

-- 
1.5.5.1

Junio C Hamano· Aug 13, 2008, 23:45 UTC · re: Don Zickus · lore

Re: [PATCH] Allow emails with boundaries to work again

Don Zickus <dzickus@redhat.com> writes:

> Recent changes to is_multipart_boundary() caused git-mailinfo to segfault.
> The reason was after handling the end of the boundary the code tried to look
> for another boundary.  Because the boundary list was empty, dereferencing
> the pointer to the top of the boundary caused the program to go boom.

We keep fixing and breaking this thing, don't we? Can we have a testcase to protect this codepath?

Don Zickus· Aug 14, 2008, 00:56 UTC · re: Junio C Hamano · lore

Re: [PATCH] Allow emails with boundaries to work again

On Wed, Aug 13, 2008 at 04:45:06PM -0700, Junio C Hamano wrote:

Show 9 quoted lines

> Don Zickus <dzickus@redhat.com> writes:
> 
> > Recent changes to is_multipart_boundary() caused git-mailinfo to segfault.
> > The reason was after handling the end of the boundary the code tried to look
> > for another boundary.  Because the boundary list was empty, dereferencing
> > the pointer to the top of the boundary caused the program to go boom.
> 
> We keep fixing and breaking this thing, don't we?  Can we have a testcase
> to protect this codepath?

Heh.  Ok I will try to work on one for tomorrow.

Cheers, Don

Junio C Hamano· Aug 14, 2008, 01:36 UTC · re: Don Zickus · lore

Re: [PATCH] Allow emails with boundaries to work again

Don Zickus <dzickus@redhat.com> writes:

Show 7 quoted lines

> Recent changes to is_multipart_boundary() caused git-mailinfo to segfault.
> The reason was after handling the end of the boundary the code tried to look
> for another boundary.  Because the boundary list was empty, dereferencing
> the pointer to the top of the boundary caused the program to go boom.
>
> The fix is to check to see if the list is empty and if so go on its merry
> way instead of looking for another boundary.

Hmm, at this point !*content_top means that we are at the outermost level and we have just seen --boundary-- which is the terminating one, haven't we? Shouldn't we be simply returning?

Don Zickus· Aug 14, 2008, 01:56 UTC · re: Junio C Hamano · lore

Re: [PATCH] Allow emails with boundaries to work again

On Wed, Aug 13, 2008 at 06:36:53PM -0700, Junio C Hamano wrote:

Show 13 quoted lines

> Don Zickus <dzickus@redhat.com> writes:
> 
> > Recent changes to is_multipart_boundary() caused git-mailinfo to segfault.
> > The reason was after handling the end of the boundary the code tried to look
> > for another boundary.  Because the boundary list was empty, dereferencing
> > the pointer to the top of the boundary caused the program to go boom.
> >
> > The fix is to check to see if the list is empty and if so go on its merry
> > way instead of looking for another boundary.
> 
> Hmm, at this point !*content_top means that we are at the outermost level
> and we have just seen --boundary-- which is the terminating one, haven't
> we?  Shouldn't we be simply returning?

That's what I originally did, but then I realized the rest of the handle_boundary() reads the next line of text, which is needed to continue processing in handle_body(). :-)

Cheers, Don