Users with SYS_ADMIN capability can add arbitrary taint flags
to the running kernel by writing to /proc/sys/kernel/tainted
or issuing the command 'sysctl -w kernel.tainted=...'.
These interface, however, are open for any integer value
and this might an invalid set of flags being committed to
the tainted_mask bitset.
This patch introduces a simple way for proc_taint() to ignore
any eventual invalid bit coming from the user input before
committing those bits to the kernel tainted_mask.
Signed-off-by: Rafael Aquini <aquini@xxxxxxxxxx>
---
Changelog:
v2: simplify the bit iterator within proc_taint(),
and silently drop out-of-range bits (akpm)
kernel/sysctl.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 8a176d8727a3..fcd46fc41206 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -2628,10 +2628,9 @@ static int proc_taint(struct ctl_table *table, int write,
* to everyone's atomic.h for this
*/
int i;
- for (i = 0; i < BITS_PER_LONG && tmptaint >> i; i++) {
- if ((tmptaint >> i) & 1)
+ for (i = 0; i < TAINT_FLAGS_COUNT; i++)
+ if ((1UL << i) & tmptaint)
add_taint(i, LOCKDEP_STILL_OK);
- }
}
return err;
--
2.25.4
