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authorRafael Aquini <aquini@redhat.com>2020-06-07 21:40:51 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-06-08 11:05:56 -0700
commite77132e75845470065768e2205727e6be52cb7f4 (patch)
treedd222e1900ff7b29db7f001e1a4fcb353a9935cc
parent60c958d8df9cfc40b745d6cd583cfbfa7525ead6 (diff)
downloadlinux-e77132e75845470065768e2205727e6be52cb7f4.tar.bz2
kernel/sysctl.c: ignore out-of-range taint bits introduced via kernel.tainted
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=...'. This interface, however, is open for any integer value and this might cause 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> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Luis Chamberlain <mcgrof@kernel.org> Cc: Kees Cook <keescook@chromium.org> Cc: Iurii Zaikin <yzaikin@google.com> Cc: "Theodore Ts'o" <tytso@mit.edu> Link: http://lkml.kernel.org/r/20200512223946.888020-1-aquini@redhat.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--kernel/sysctl.c5
1 files changed, 2 insertions, 3 deletions
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index f69d581d39c3..db1ce7af2563 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -880,10 +880,9 @@ static int proc_taint(struct ctl_table *table, int write,
* Poor man's atomic or. Not worth adding a primitive
* to everyone's atomic.h for this
*/
- 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;