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 <[email protected]> --- 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
