Re: avoid leak upon failed realloc

Theodore Tso
2007-06-22T06:42:01Z

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On Mon, Jun 18, 2007 at 04:10:44PM +0200, Jim Meyering wrote:
> Here's a tiny fix to avoid a leak when realloc fails:
>
> 2007-06-16 Jim Meyering <jim@meyering.net>
>
> * tdb.c (tdb_append): Don't leak a buffer when realloc fails.

Hi Jim,

Thanks for the patch! I actually automatically build the
tdb.c file from the Samba SVN tree (with a series of patches and
scripts) at:

svn://svnanon.samba.org/samba/branches/SAMBA_4_0/source/lib/tdb

So I'm going to forward this patch (attached) to the Samba developers.
It appears to apply cleanly to .../source/lib/tdb/common/tdb.c. Once
they commit it into their SVN tree, I can just pick it up from there.

Regards,

- Ted

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Dave Kleikamp <shaggy@linux.vnet.ibm.com> wrote:
> Not a big deal, but this part could be simplified to:
>
> if (new_dptr == NULL)
> free(dbuf.dptr);
> dbuf.dptr = new_dptr;

Of course!
Thanks!

In case it helps, here's the updated patch:

Here's a tiny fix to avoid a leak when realloc fails:

2007-06-16 Jim Meyering <jim@meyering.net>

* tdb.c (tdb_append): Don't leak a buffer when realloc fails.

diff -r 777972a573b3 lib/ext2fs/tdb.c
--- a/lib/ext2fs/tdb.c Fri Jun 15 18:05:09 2007 +0200
+++ b/lib/ext2fs/tdb.c Mon Jun 18 16:08:24 2007 +0200
@@ -3460,8 +3460,12 @@ int tdb_append(struct tdb_context *tdb,
if (dbuf.dptr == NULL) {
dbuf.dptr = (unsigned char *)malloc(new_dbuf.dsize);
} else {
- dbuf.dptr = (unsigned char *)realloc(dbuf.dptr,
- dbuf.dsize + new_dbuf.dsize);
+ unsigned char *new_dptr
+ = (unsigned char *)realloc(dbuf.dptr,
+ dbuf.dsize + new_dbuf.dsize);
+ if (new_dptr == NULL)
+ free(dbuf.dptr);
+ dbuf.dptr = new_dptr;
}

if (dbuf.dptr == NULL) {

Signed-off-by: Jim Meyering <jim@meyering.net>
-
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