On Tue, May 07, 2019 at 02:41:13PM +0200, Pavel Machek wrote: > > It seems to me that we still allow overflow if count == ~0. We'll then > allocate 0 bytes but copy ~0 bytes. That does not sound healthy. > > Fixes: f08b18266c7116e2ec6885dd53a928f580060a71 > > Signed-off-by: Pavel Machek <pa...@denx.de> > > diff --git a/drivers/hwtracing/stm/core.c b/drivers/hwtracing/stm/core.c > index c7ba8ac..8846fca 100644 > --- a/drivers/hwtracing/stm/core.c > +++ b/drivers/hwtracing/stm/core.c > @@ -631,7 +631,7 @@ static ssize_t stm_char_write(struct file *file, const > char __user *buf, > char *kbuf; > int err; > > - if (count + 1 > PAGE_SIZE) > + if (count > PAGE_SIZE - 1) > count = PAGE_SIZE - 1;
The "count" variable should all be checked in vfs_write(). count + off is checked in rw_verify_area() and count is capped at MAX_RW_COUNT. #define MAX_RW_COUNT (INT_MAX & PAGE_MASK) regards, dan carpenter
