@@ -494,6 +494,8 @@ static void nvec_tx_completed(struct nvec_chip *nvec)
static void nvec_rx_completed(struct nvec_chip *nvec)
{
if (nvec->rx->pos != nvec_msg_size(nvec->rx)) {
+ unsigned char msg_type = nvec->rx->data[0];
+
dev_err(nvec->dev, "RX incomplete: Expected %u bytes, got %u\n",
(uint)nvec_msg_size(nvec->rx),
(uint)nvec->rx->pos);
@@ -502,7 +504,7 @@ static void nvec_rx_completed(struct nvec_chip *nvec)
nvec->state = 0;
/* Battery quirk - Often incomplete, and likes to crash */
- if (nvec->rx->data[0] == NVEC_BAT)
+ if (msg_type == NVEC_BAT)
complete(&nvec->ec_transfer);
return;
In nvec_rx_completed(), when an incomplete RX transfer is detected, nvec_msg_free() is called to return the message back to the pool by clearing its 'used' atomic flag. Immediately after this, the code accesses nvec->rx->data[0] to check the message type. Since nvec_msg_free() marks the pool slot as available via atomic_set(), any concurrent or subsequent call to nvec_msg_alloc() could claim that same slot and overwrite its data[] array. Reading nvec->rx->data[0] after freeing the message is therefore a use-after-free. Fix this by saving the message type byte before calling nvec_msg_free(), then using the saved value for the battery quirk check. Fixes: d6bdcf2e1019 ("staging: nvec: Add battery quirk to ignore incomplete responses") Reviewed-by: Dan Carpenter <error27@gmail.com> Signed-off-by: Alexandru Hossu <hossu.alexandru@gmail.com> --- drivers/staging/nvec/nvec.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)