[PATCH AUTOSEL 6.2 11/20] wifi: mt76: mt7921: Fix use-after-free in fw features query.

Sasha Levin
2023-04-13T02:37:50Z

From: Ben Greear <greearb@candelatech.com>

[ Upstream commit 2ceb76f734e37833824b7fab6af17c999eb48d2b ]

Stop referencing 'features' memory after release_firmware is called.

Fixes this crash:

RIP: 0010:mt7921_check_offload_capability+0x17d
mt7921_pci_probe+0xca/0x4b0
...

Signed-off-by: Ben Greear <greearb@candelatech.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Acked-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/51fd8f76494348aa9ecbf0abc471ebe47a983dfd.1679502607.git.lorenzo@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/wireless/mediatek/mt76/mt7921/init.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7921/init.c b/drivers/net/wireless/mediatek/mt76/mt7921/init.c
index d4b681d7e1d22..f2c6ec4d8e2ee 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7921/init.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7921/init.c
@@ -162,12 +162,12 @@ mt7921_mac_init_band(struct mt7921_dev *dev, u8 band)

u8 mt7921_check_offload_capability(struct device *dev, const char *fw_wm)
{
- struct mt7921_fw_features *features = NULL;
const struct mt76_connac2_fw_trailer *hdr;
struct mt7921_realease_info *rel_info;
const struct firmware *fw;
int ret, i, offset = 0;
const u8 *data, *end;
+ u8 offload_caps = 0;

ret = request_firmware(&fw, fw_wm, dev);
if (ret)
@@ -199,7 +199,10 @@ u8 mt7921_check_offload_capability(struct device *dev, const char *fw_wm)
data += sizeof(*rel_info);

if (rel_info->tag == MT7921_FW_TAG_FEATURE) {
+ struct mt7921_fw_features *features;
+
features = (struct mt7921_fw_features *)data;
+ offload_caps = features->data;
break;
}

@@ -209,7 +212,7 @@ u8 mt7921_check_offload_capability(struct device *dev, const char *fw_wm)
out:
release_firmware(fw);

- return features ? features->data : 0;
+ return offload_caps;
}
EXPORT_SYMBOL_GPL(mt7921_check_offload_capability);

--
2.39.2