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| author | Jiri Bohac <jbohac@suse.cz> | 2014-04-18 17:23:11 +0200 |
|---|---|---|
| committer | Jiri Slaby <jslaby@suse.cz> | 2014-06-06 11:40:22 +0200 |
| commit | da2eadf4eedb2658cb029ba98b22490c6dcc88a0 (patch) | |
| tree | 3bc1a7647a45bdf506825efe3cbbf87e0ab18a56 /kernel | |
| parent | 5fc7e548c184705e46aac7d5149febc95001691f (diff) | |
| download | lwn-da2eadf4eedb2658cb029ba98b22490c6dcc88a0.tar.gz lwn-da2eadf4eedb2658cb029ba98b22490c6dcc88a0.zip | |
timer: Prevent overflow in apply_slack
commit 98a01e779f3c66b0b11cd7e64d531c0e41c95762 upstream.
On architectures with sizeof(int) < sizeof (long), the
computation of mask inside apply_slack() can be undefined if the
computed bit is > 32.
E.g. with: expires = 0xffffe6f5 and slack = 25, we get:
expires_limit = 0x20000000e
bit = 33
mask = (1 << 33) - 1 /* undefined */
On x86, mask becomes 1 and and the slack is not applied properly.
On s390, mask is -1, expires is set to 0 and the timer fires immediately.
Use 1UL << bit to solve that issue.
Suggested-by: Deborah Townsend <dstownse@us.ibm.com>
Signed-off-by: Jiri Bohac <jbohac@suse.cz>
Link: http://lkml.kernel.org/r/20140418152310.GA13654@midget.suse.cz
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/timer.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/timer.c b/kernel/timer.c index 4296d13db3d1..4addfa27f67d 100644 --- a/kernel/timer.c +++ b/kernel/timer.c @@ -822,7 +822,7 @@ unsigned long apply_slack(struct timer_list *timer, unsigned long expires) bit = find_last_bit(&mask, BITS_PER_LONG); - mask = (1 << bit) - 1; + mask = (1UL << bit) - 1; expires_limit = expires_limit & ~(mask); |