From patchwork Tue Feb 5 22:06:45 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [56/93] drm/radeon: fix a rare case of double kfree From: Herton Ronaldo Krzesinski X-Patchwork-Id: 218420 Message-Id: <1360102042-10732-57-git-send-email-herton.krzesinski@canonical.com> To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Ilija Hadzic , Alex Deucher Date: Tue, 5 Feb 2013 20:06:45 -0200 3.5.7.5 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Ilija Hadzic commit 1da80cfa8727abf404fcee44d04743febea54069 upstream. If one (but not both) allocations of p->chunks[].kpage[] in radeon_cs_parser_init fail, the error path will free the successfully allocated page, but leave a stale pointer value in the kpage[] field. This will later cause a double-free when radeon_cs_parser_fini is called. This patch fixes the issue by forcing both pointers to NULL after kfree in the error path. The circumstances under which the problem happens are very rare. The card must be AGP and the system must run out of kmalloc area just at the right time so that one allocation succeeds, while the other fails. Signed-off-by: Ilija Hadzic Cc: Herton Ronaldo Krzesinski Signed-off-by: Alex Deucher Signed-off-by: Herton Ronaldo Krzesinski --- drivers/gpu/drm/radeon/radeon_cs.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/gpu/drm/radeon/radeon_cs.c b/drivers/gpu/drm/radeon/radeon_cs.c index c71652b..a0f3404 100644 --- a/drivers/gpu/drm/radeon/radeon_cs.c +++ b/drivers/gpu/drm/radeon/radeon_cs.c @@ -281,6 +281,8 @@ int radeon_cs_parser_init(struct radeon_cs_parser *p, void *data) p->chunks[p->chunk_ib_idx].kpage[1] == NULL) { kfree(p->chunks[p->chunk_ib_idx].kpage[0]); kfree(p->chunks[p->chunk_ib_idx].kpage[1]); + p->chunks[p->chunk_ib_idx].kpage[0] = NULL; + p->chunks[p->chunk_ib_idx].kpage[1] = NULL; return -ENOMEM; } }