[PATCH linux-next] drm/radeon: Avoid NULL pointer dereference from atom_index_iio() allocation failure

[Tim Gardner]

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 at linux.ie>
Cc: Alex Deucher <alexander.deucher at amd.com>
Cc: "Michel D?nzer" <michel.daenzer at amd.com>
Cc: Dave Airlie <airlied at redhat.com>
Cc: "Christian K?nig" <christian.koenig at amd.com>
Cc: Jerome Glisse <jglisse at redhat.com>
Cc: dri-devel at lists.freedesktop.org
Signed-off-by: Tim Gardner <tim.gardner at canonical.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