# [PATCH] xdiff/xmerge: fix memory leak in xdl_merge 4 messages from 2016-02-23 to 2016-02-23. Participants: Patrick Steinhardt, Johannes Schindelin. Thread: https://gitlist.dev/t/41481 ## Patrick Steinhardt, 2016-02-23 08:45 Subject: [PATCH] xdiff/xmerge: fix memory leak in xdl_merge Message-ID: <1456217151-16473-1-git-send-email-ps@pks.im> URL: https://gitlist.dev/e/1456217151-16473-1-git-send-email-ps%40pks.im ``` 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 --- 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 ``` ## Johannes Schindelin, 2016-02-23 10:09 Subject: Re: [PATCH] xdiff/xmerge: fix memory leak in xdl_merge Message-ID: URL: https://gitlist.dev/e/alpine.DEB.2.20.1602231108260.3152%40virtualbox In-Reply-To: <1456217151-16473-1-git-send-email-ps@pks.im> ``` 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 || ``` ## Patrick Steinhardt, 2016-02-23 11:51 Subject: Re: [PATCH] xdiff/xmerge: fix memory leak in xdl_merge Message-ID: <20160223115135.GA977@pks-pc.localdomain> URL: https://gitlist.dev/e/20160223115135.GA977%40pks-pc.localdomain In-Reply-To: ``` 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 ``` ## Patrick Steinhardt, 2016-02-23 11:59 Subject: [PATCH v2] xdiff/xmerge: fix memory leak in xdl_merge Message-ID: <1456228757-19333-1-git-send-email-ps@pks.im> URL: https://gitlist.dev/e/1456228757-19333-1-git-send-email-ps%40pks.im In-Reply-To: <1456217151-16473-1-git-send-email-ps@pks.im> ``` 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 Signed-off-by: Patrick Steinhardt --- 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 ```