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authorNick Desaulniers <nick.desaulniers@gmail.com>2017-12-28 22:11:36 -0500
committerThomas Gleixner <tglx@linutronix.de>2018-01-04 14:57:10 +0100
commit29f1b2b0fecfae69e31833836f1da3136696eee5 (patch)
tree4c299cbdc55a3cc3236e8ef3cc80e6af51ee4a57 /kernel/time/posix-clock.c
parent00a5ae218d57741088068799b810416ac249a9ce (diff)
downloadlinux-29f1b2b0fecfae69e31833836f1da3136696eee5.tar.bz2
posix-timers: Prevent UB from shifting negative signed value
Shifting a negative signed number is undefined behavior. Looking at the macros MAKE_PROCESS_CPUCLOCK and FD_TO_CLOCKID, it seems that the subexpression: (~(clockid_t) (pid) << 3) where clockid_t resolves to a signed int, which once negated, is undefined behavior to shift the value of if the results thus far are negative. It was further suggested to make these macros into inline functions. Suggested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Nick Desaulniers <nick.desaulniers@gmail.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Dimitri Sivanich <sivanich@hpe.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: linux-kselftest@vger.kernel.org Cc: Shuah Khan <shuah@kernel.org> Cc: Deepa Dinamani <deepa.kernel@gmail.com> Link: https://lkml.kernel.org/r/1514517100-18051-1-git-send-email-nick.desaulniers@gmail.com
Diffstat (limited to 'kernel/time/posix-clock.c')
-rw-r--r--kernel/time/posix-clock.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/time/posix-clock.c b/kernel/time/posix-clock.c
index 17cdc554c9fe..cc91d90abd84 100644
--- a/kernel/time/posix-clock.c
+++ b/kernel/time/posix-clock.c
@@ -216,7 +216,7 @@ struct posix_clock_desc {
static int get_clock_desc(const clockid_t id, struct posix_clock_desc *cd)
{
- struct file *fp = fget(CLOCKID_TO_FD(id));
+ struct file *fp = fget(clockid_to_fd(id));
int err = -EINVAL;
if (!fp)