[lkml]   [2002]   [Feb]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH] read() from driverfs files can read more bytes then requested

On Thu, 7 Feb 2002, Andrey Panin wrote:

> Hi all,
> small program below crashes on read() from driverfs file:
> int main(void)
> {
> int fd, ret;
> char buf[16];
> fd = open("/var/driver/root/pci0/status", 0);
> ret = read(fd, buf, sizeof(buf));
> close(fd);
> }
> it's because driverfs_read_file() function blindly uses entry->show()
> return value without sanity check. As a result userspace process requested
> 16 bytes, but got ~45 and smashed stack as a bonus. You can also get this
> effect pressing F3 in Midnight Commander on driverfs files.
> Attached patch adds check that returned value is less then requested
> byte count. I know that actual callback function device_read_status()
> should also be fixed, but I found this bug after midnight and
> decided to sleep a little :)

That sanity check was in there, once upon a time. However, in moving the
weight from the driver callbacks to the driverfs read_file() and
write_file(), it must have got dropped...

Thank you. It's been applied and will be pushed forward.


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2005-03-22 13:24    [W:0.026 / U:1.816 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site