linux-kernel - [PATCH linux-next] drm/radeon: Avoid NULL pointer dereference from atom_index

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Message-Id: <1360618472-14821-1-git-send-email-tim.gardner@canonical.com>
Date:	Mon, 11 Feb 2013 14:34:32 -0700
From:	Tim Gardner <tim.gardner@...onical.com>
To:	linux-kernel@...r.kernel.org
Cc:	Tim Gardner <tim.gardner@...onical.com>,
	David Airlie <airlied@...ux.ie>,
	Alex Deucher <alexander.deucher@....com>,
	Michel Dänzer <michel.daenzer@....com>,
	Dave Airlie <airlied@...hat.com>,
	Christian König <christian.koenig@....com>,
	Jerome Glisse <jglisse@...hat.com>,
	dri-devel@...ts.freedesktop.org
Subject: [PATCH linux-next] drm/radeon: Avoid NULL pointer dereference from atom_index_iio() allocation failure

Smatch anlysis:

drivers/gpu/drm/radeon/atom.c:1242 atom_index_iio() error: potential null
 dereference 'ctx->iio'.  (kzalloc returns null)

Also cleaned up some checks before calls to kfree(). kfree(NULL) is OK.

Cc: David Airlie <airlied@...ux.ie>
Cc: Alex Deucher <alexander.deucher@....com>
Cc: "Michel Dänzer" <michel.daenzer@....com>
Cc: Dave Airlie <airlied@...hat.com>
Cc: "Christian König" <christian.koenig@....com>
Cc: Jerome Glisse <jglisse@...hat.com>
Cc: dri-devel@...ts.freedesktop.org
Signed-off-by: Tim Gardner <tim.gardner@...onical.com>
---
 drivers/gpu/drm/radeon/atom.c          |    9 +++++++--
 drivers/gpu/drm/radeon/radeon_device.c |    9 ++++++++-
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/radeon/atom.c b/drivers/gpu/drm/radeon/atom.c
index 5ce9bf5..46a9c37 100644
--- a/drivers/gpu/drm/radeon/atom.c
+++ b/drivers/gpu/drm/radeon/atom.c
@@ -1238,6 +1238,8 @@ static int atom_iio_len[] = { 1, 2, 3, 3, 3, 3, 4, 4, 4, 3 };
 static void atom_index_iio(struct atom_context *ctx, int base)
 {
 	ctx->iio = kzalloc(2 * 256, GFP_KERNEL);
+	if (!ctx->iio)
+		return;
 	while (CU8(base) == ATOM_IIO_START) {
 		ctx->iio[CU8(base + 1)] = base + 2;
 		base += 2;
@@ -1287,6 +1289,10 @@ struct atom_context *atom_parse(struct card_info *card, void *bios)
 	ctx->cmd_table = CU16(base + ATOM_ROM_CMD_PTR);
 	ctx->data_table = CU16(base + ATOM_ROM_DATA_PTR);
 	atom_index_iio(ctx, CU16(ctx->data_table + ATOM_DATA_IIO_PTR) + 4);
+	if (!ctx->iio) {
+		atom_destroy(ctx);
+		return NULL;
+	}
 
 	str = CSTR(CU16(base + ATOM_ROM_MSG_PTR));
 	while (*str && ((*str == '\n') || (*str == '\r')))
@@ -1335,8 +1341,7 @@ int atom_asic_init(struct atom_context *ctx)
 
 void atom_destroy(struct atom_context *ctx)
 {
-	if (ctx->iio)
-		kfree(ctx->iio);
+	kfree(ctx->iio);
 	kfree(ctx);
 }
 
diff --git a/drivers/gpu/drm/radeon/radeon_device.c b/drivers/gpu/drm/radeon/radeon_device.c
index 8794de1..44b8034 100644
--- a/drivers/gpu/drm/radeon/radeon_device.c
+++ b/drivers/gpu/drm/radeon/radeon_device.c
@@ -759,6 +759,11 @@ int radeon_atombios_init(struct radeon_device *rdev)
 	atom_card_info->pll_write = cail_pll_write;
 
 	rdev->mode_info.atom_context = atom_parse(atom_card_info, rdev->bios);
+	if (!rdev->mode_info.atom_context) {
+		radeon_atombios_fini(rdev);
+		return -ENOMEM;
+	}
+
 	mutex_init(&rdev->mode_info.atom_context->mutex);
 	radeon_atom_initialize_bios_scratch_regs(rdev->ddev);
 	atom_allocate_fb_scratch(rdev->mode_info.atom_context);
@@ -778,9 +783,11 @@ void radeon_atombios_fini(struct radeon_device *rdev)
 {
 	if (rdev->mode_info.atom_context) {
 		kfree(rdev->mode_info.atom_context->scratch);
-		kfree(rdev->mode_info.atom_context);
 	}
+	kfree(rdev->mode_info.atom_context);
+	rdev->mode_info.atom_context = NULL;
 	kfree(rdev->mode_info.atom_card_info);
+	rdev->mode_info.atom_card_info = NULL;
 }
 
 /* COMBIOS */
-- 
1.7.9.5

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