Protect access to fore200e->available_cell_rate with rate_mtx lock to prevent potential data race.
In this case, since the update depends on a prior read, a data race could lead to a wrong fore200e.available_cell_rate value.
The field fore200e.available_cell_rate is generally protected by the lock fore200e.rate_mtx when accessed. In all other read and write cases, this field is consistently protected by the lock, except for this case and during initialization.
This potential bug was detected by our experimental static analysis tool, which analyzes locking APIs and paired functions to identify data races and atomicity violations.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Signed-off-by: Gui-Dong Han hanguidong02@gmail.com Reviewed-by: Simon Horman horms@kernel.org --- v2: * Added a description of the data race hazard in fore200e_open(), as suggested by Jakub Kicinski and Simon Horman.
REPOST: * Reposting v2 as it seems to have been overlooked. --- drivers/atm/fore200e.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/drivers/atm/fore200e.c b/drivers/atm/fore200e.c index 4fea1149e003..f62e38571440 100644 --- a/drivers/atm/fore200e.c +++ b/drivers/atm/fore200e.c @@ -1374,7 +1374,9 @@ fore200e_open(struct atm_vcc *vcc)
vcc->dev_data = NULL;
+ mutex_lock(&fore200e->rate_mtx); fore200e->available_cell_rate += vcc->qos.txtp.max_pcr; + mutex_unlock(&fore200e->rate_mtx);
kfree(fore200e_vcc); return -EINVAL;