[PATCH] xdiff/xmerge: fix memory leak in xdl_merge

[PATCH] xdiff/xmerge: fix memory leak in xdl_merge

[Patrick Steinhardt]

When building the script for the second file that is to be merged
we have already allocated memory for data structures related to
the first file. When we encounter an error in building the second
script we only free allocated memory related to the second file
before erroring out.

Fix this memory leak by also releasing allocated memory related
to the first file.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
---
 xdiff/xmerge.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/xdiff/xmerge.c b/xdiff/xmerge.c
index d98f430..d04eb46 100644
--- a/xdiff/xmerge.c
+++ b/xdiff/xmerge.c
@@ -654,6 +654,8 @@ int xdl_merge(mmfile_t *orig, mmfile_t *mf1, mmfile_t *mf2,
 	if (xdl_change_compact(&xe2.xdf1, &xe2.xdf2, xpp->flags) < 0 ||
 	    xdl_change_compact(&xe2.xdf2, &xe2.xdf1, xpp->flags) < 0 ||
 	    xdl_build_script(&xe2, &xscr2) < 0) {
+		xdl_free_script(xscr1);
+		xdl_free_env(&xe1);
 		xdl_free_env(&xe2);
 		return -1;
 	}
-- 
2.7.1

Re: [PATCH] xdiff/xmerge: fix memory leak in xdl_merge

[Johannes Schindelin]

Hi Patrick,

On Tue, 23 Feb 2016, Patrick Steinhardt wrote:

> When building the script for the second file that is to be merged
> we have already allocated memory for data structures related to
> the first file. When we encounter an error in building the second
> script we only free allocated memory related to the second file
> before erroring out.

ACK.

I wonder, though, whether we need this in addition:

-- snipsnap --
t a/xdiff/xmerge.c b/xdiff/xmerge.c
index 625198e..e5c8745 100644
--- a/xdiff/xmerge.c
+++ b/xdiff/xmerge.c
@@ -579,8 +579,11 @@ int xdl_merge(mmfile_t *orig, mmfile_t *mf1, mmfile_t
*mf2,
 	result->ptr = NULL;
 	result->size = 0;
 
-	if (xdl_do_diff(orig, mf1, xpp, &xe1) < 0 ||
-			xdl_do_diff(orig, mf2, xpp, &xe2) < 0) {
+	if (xdl_do_diff(orig, mf1, xpp, &xe1) < 0) {
+		return -1;
+	}
+	if (xdl_do_diff(orig, mf2, xpp, &xe2) < 0) {
+		xdl_free_env(&xe1);
 		return -1;
 	}
 	if (xdl_change_compact(&xe1.xdf1, &xe1.xdf2, xpp->flags) < 0 ||

Re: [PATCH] xdiff/xmerge: fix memory leak in xdl_merge

[Patrick Steinhardt]

[-- Attachment #1: Type: text/plain, Size: 1437 bytes --]

On Tue, Feb 23, 2016 at 11:09:50AM +0100, Johannes Schindelin wrote:
> Hi Patrick,
> 
> On Tue, 23 Feb 2016, Patrick Steinhardt wrote:
> 
> > When building the script for the second file that is to be merged
> > we have already allocated memory for data structures related to
> > the first file. When we encounter an error in building the second
> > script we only free allocated memory related to the second file
> > before erroring out.
> 
> ACK.
> 
> I wonder, though, whether we need this in addition:
> 
> -- snipsnap --
> t a/xdiff/xmerge.c b/xdiff/xmerge.c
> index 625198e..e5c8745 100644
> --- a/xdiff/xmerge.c
> +++ b/xdiff/xmerge.c
> @@ -579,8 +579,11 @@ int xdl_merge(mmfile_t *orig, mmfile_t *mf1, mmfile_t
> *mf2,
>  	result->ptr = NULL;
>  	result->size = 0;
>  
> -	if (xdl_do_diff(orig, mf1, xpp, &xe1) < 0 ||
> -			xdl_do_diff(orig, mf2, xpp, &xe2) < 0) {
> +	if (xdl_do_diff(orig, mf1, xpp, &xe1) < 0) {
> +		return -1;
> +	}
> +	if (xdl_do_diff(orig, mf2, xpp, &xe2) < 0) {
> +		xdl_free_env(&xe1);
>  		return -1;
>  	}
>  	if (xdl_change_compact(&xe1.xdf1, &xe1.xdf2, xpp->flags) < 0 ||

Oh, yes, this is required. I am somewhat confused by all the
pointers being passed around there, it is not immediately obvious
which pointers are being allocated and which not when you are not
intimate with the code base.

So thanks for pointing this out. Will post v2 soon.

Patrick

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[PATCH v2] xdiff/xmerge: fix memory leak in xdl_merge

[Patrick Steinhardt]

When building the script for the second file that is to be merged
we have already allocated memory for data structures related to
the first file. When we encounter an error in building the second
script we only free allocated memory related to the second file
before erroring out.

Fix this memory leak by also releasing allocated memory related
to the first file.

Helped-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
---
 xdiff/xmerge.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/xdiff/xmerge.c b/xdiff/xmerge.c
index d98f430..f338ad6 100644
--- a/xdiff/xmerge.c
+++ b/xdiff/xmerge.c
@@ -641,8 +641,11 @@ int xdl_merge(mmfile_t *orig, mmfile_t *mf1, mmfile_t *mf2,
 	result->ptr = NULL;
 	result->size = 0;
 
-	if (xdl_do_diff(orig, mf1, xpp, &xe1) < 0 ||
-			xdl_do_diff(orig, mf2, xpp, &xe2) < 0) {
+	if (xdl_do_diff(orig, mf1, xpp, &xe1) < 0) {
+		return -1;
+	}
+	if (xdl_do_diff(orig, mf2, xpp, &xe2) < 0) {
+		xdl_free_env(&xe1);
 		return -1;
 	}
 	if (xdl_change_compact(&xe1.xdf1, &xe1.xdf2, xpp->flags) < 0 ||
@@ -654,6 +657,8 @@ int xdl_merge(mmfile_t *orig, mmfile_t *mf1, mmfile_t *mf2,
 	if (xdl_change_compact(&xe2.xdf1, &xe2.xdf2, xpp->flags) < 0 ||
 	    xdl_change_compact(&xe2.xdf2, &xe2.xdf1, xpp->flags) < 0 ||
 	    xdl_build_script(&xe2, &xscr2) < 0) {
+		xdl_free_script(xscr1);
+		xdl_free_env(&xe1);
 		xdl_free_env(&xe2);
 		return -1;
 	}
-- 
2.7.1