Hi Qiu-ji Chen, On 30/10/2024 07:48, Qiu-ji Chen wrote: > Atomicity violation occurs when the fmc_send_cmd() function is executed > simultaneously with the modification of the fmdev->resp_skb value. > Consider a scenario where, after passing the validity check within the > function, a non-null fmdev->resp_skb variable is assigned a null value. > This results in an invalid fmdev->resp_skb variable passing the validity > check. As seen in the later part of the function, skb = fmdev->resp_skb; > when the invalid fmdev->resp_skb passes the check, a null pointer > dereference error may occur at line 478, evt_hdr = (void *)skb->data; > > To address this issue, it is recommended to include the validity check of > fmdev->resp_skb within the locked section of the function. This > modification ensures that the value of fmdev->resp_skb does not change > during the validation process, thereby maintaining its validity. > > This possible bug is found by an experimental static analysis tool > developed by our team. This tool analyzes the locking APIs > to extract function pairs that can be concurrently executed, and then > analyzes the instructions in the paired functions to identify possible > concurrency bugs including data races and atomicity violations. FYI, since this driver will be removed soon, I'm not taking this patch. See this patch for the driver removal: https://patchwork.linuxtv.org/project/linux-media/patch/20241028083030.26351-1-lukas.bulwahn@xxxxxxxxxx/ Regards, Hans > > Fixes: e8454ff7b9a4 ("[media] drivers:media:radio: wl128x: FM Driver Common sources") > Cc: stable@xxxxxxxxxxxxxxx > Signed-off-by: Qiu-ji Chen <chenqiuji666@xxxxxxxxx> > --- > drivers/media/radio/wl128x/fmdrv_common.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/media/radio/wl128x/fmdrv_common.c b/drivers/media/radio/wl128x/fmdrv_common.c > index 3d36f323a8f8..4d032436691c 100644 > --- a/drivers/media/radio/wl128x/fmdrv_common.c > +++ b/drivers/media/radio/wl128x/fmdrv_common.c > @@ -466,11 +466,12 @@ int fmc_send_cmd(struct fmdev *fmdev, u8 fm_op, u16 type, void *payload, > jiffies_to_msecs(FM_DRV_TX_TIMEOUT) / 1000); > return -ETIMEDOUT; > } > + spin_lock_irqsave(&fmdev->resp_skb_lock, flags); > if (!fmdev->resp_skb) { > + spin_unlock_irqrestore(&fmdev->resp_skb_lock, flags); > fmerr("Response SKB is missing\n"); > return -EFAULT; > } > - spin_lock_irqsave(&fmdev->resp_skb_lock, flags); > skb = fmdev->resp_skb; > fmdev->resp_skb = NULL; > spin_unlock_irqrestore(&fmdev->resp_skb_lock, flags);
