lkml.org 
[lkml]   [2020]   [May]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v2] kernel: sysctl: ignore out-of-range taint bits introduced via kernel.tainted
Date
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@redhat.com>
---
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
\
 
 \ /
  Last update: 2020-05-13 00:41    [W:0.284 / U:0.008 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site