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 :)
Best regards.
-- Andrey Panin | Embedded systems software engineer pazke@orbita1.ru | PGP key: wwwkeys.eu.pgp.net
This archive was generated by hypermail 2b29 : Thu Feb 07 2002 - 21:00:59 EST