staging: istallion: fix arbitrary kernel memory reads/writes
stli_brdstats is defined as global variable. After de-BKL-ization in
the patch b4eda9cb48eac1b7 an access to the variable is not serialized
anymore. This leads to the race window between the check and the use
in stli_getbrdstats():
if (copy_from_user(&stli_brdstats, bp, sizeof(combrd_t)))
return -EFAULT;
if (stli_brdstats.brd >= STL_MAXBRDS) <<<
return -ENODEV;
brdp = stli_brds[stli_brdstats.brd]; <<<
If one process calls COM_GETBRDSTATS ioctl() with sane .brd, second
process calls COM_GETBRDSTATS ioctl() with invalid .brd, and the
second process' copy_from_user() executes exactly between the check and
stli_brds[] indexation of the first process, then the first process gets
contents of memory at *stli_brds[stli_brdstats.brd] address. Also
the resulting .nrpanels field may be too big, in this case
stli_brdstats.panels array overflows.
Signed-off-by: Vasiliy Kulikov <segoon@openwall.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
1 file changed