diff options
Diffstat (limited to 'pkgs/servers/x11/xorg/xorgserver-cve-2013-4396.patch')
-rw-r--r-- | pkgs/servers/x11/xorg/xorgserver-cve-2013-4396.patch | 75 |
1 files changed, 75 insertions, 0 deletions
diff --git a/pkgs/servers/x11/xorg/xorgserver-cve-2013-4396.patch b/pkgs/servers/x11/xorg/xorgserver-cve-2013-4396.patch new file mode 100644 index 000000000000..4b6727e61c05 --- /dev/null +++ b/pkgs/servers/x11/xorg/xorgserver-cve-2013-4396.patch @@ -0,0 +1,75 @@ +From 7bddc2ba16a2a15773c2ea8947059afa27727764 Mon Sep 17 00:00:00 2001 +From: Alan Coopersmith <alan.coopersmith@oracle.com> +Date: Mon, 16 Sep 2013 21:47:16 -0700 +Subject: [PATCH] Avoid use-after-free in dix/dixfonts.c: doImageText() + [CVE-2013-4396] + +Save a pointer to the passed in closure structure before copying it +and overwriting the *c pointer to point to our copy instead of the +original. If we hit an error, once we free(c), reset c to point to +the original structure before jumping to the cleanup code that +references *c. + +Since one of the errors being checked for is whether the server was +able to malloc(c->nChars * itemSize), the client can potentially pass +a number of characters chosen to cause the malloc to fail and the +error path to be taken, resulting in the read from freed memory. + +Since the memory is accessed almost immediately afterwards, and the +X server is mostly single threaded, the odds of the free memory having +invalid contents are low with most malloc implementations when not using +memory debugging features, but some allocators will definitely overwrite +the memory there, leading to a likely crash. + +Reported-by: Pedro Ribeiro <pedrib@gmail.com> +Signed-off-by: Alan Coopersmith <alan.coopersmith@oracle.com> +Reviewed-by: Julien Cristau <jcristau@debian.org> +--- + dix/dixfonts.c | 5 +++++ + 1 file changed, 5 insertions(+) + +diff --git a/dix/dixfonts.c b/dix/dixfonts.c +index feb765d..2e34d37 100644 +--- a/dix/dixfonts.c ++++ b/dix/dixfonts.c +@@ -1425,6 +1425,7 @@ doImageText(ClientPtr client, ITclosurePtr c) + GC *pGC; + unsigned char *data; + ITclosurePtr new_closure; ++ ITclosurePtr old_closure; + + /* We're putting the client to sleep. We need to + save some state. Similar problem to that handled +@@ -1436,12 +1437,14 @@ doImageText(ClientPtr client, ITclosurePtr c) + err = BadAlloc; + goto bail; + } ++ old_closure = c; + *new_closure = *c; + c = new_closure; + + data = malloc(c->nChars * itemSize); + if (!data) { + free(c); ++ c = old_closure; + err = BadAlloc; + goto bail; + } +@@ -1452,6 +1455,7 @@ doImageText(ClientPtr client, ITclosurePtr c) + if (!pGC) { + free(c->data); + free(c); ++ c = old_closure; + err = BadAlloc; + goto bail; + } +@@ -1464,6 +1468,7 @@ doImageText(ClientPtr client, ITclosurePtr c) + FreeScratchGC(pGC); + free(c->data); + free(c); ++ c = old_closure; + err = BadAlloc; + goto bail; + } +-- +1.7.9.2 |