diff options
| author | Rasmus Villemoes <linux@rasmusvillemoes.dk> | 2017-10-31 00:35:47 +0300 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2017-11-13 01:25:40 +0300 |
| commit | ffc661c99f621152d5fdcf53f9df0d48c326318b (patch) | |
| tree | 541eeda902b4a35a7fab7fd92cdf9691a3e691f1 | |
| parent | 306eb5a38dfc1a4c8a5c910c9844da6a97f2b9a4 (diff) | |
| download | linux-ffc661c99f621152d5fdcf53f9df0d48c326318b.tar.xz | |
genirq: Fix type of shifting literal 1 in __setup_irq()
If ffz() ever returns a value >= 31 then the following shift is undefined
behaviour because the literal 1 which gets shifted is treated as signed
integer.
In practice, the bug is probably harmless, since the first undefined shift
count is 31 which results - ignoring UB - in (int)(0x80000000). This gets
sign extended so bit 32-63 will be set as well and all subsequent
__setup_irq() calls would just end up hitting the -EBUSY branch.
However, a sufficiently aggressive optimizer may use the UB of 1<<31
to decide that doesn't happen, and hence elide the sign-extension
code, so that subsequent calls can indeed get ffz > 31.
In any case, the right thing to do is to make the literal 1UL.
[ tglx: For this to happen a single interrupt would have to be shared by 32
devices. Hardware like that does not exist and would have way more
problems than that. ]
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20171030213548.16831-1-linux@rasmusvillemoes.dk
| -rw-r--r-- | kernel/irq/manage.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c index c65f282cbc9a..6a1bf9dc7a6a 100644 --- a/kernel/irq/manage.c +++ b/kernel/irq/manage.c @@ -1289,7 +1289,7 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new) * thread_mask assigned. See the loop above which or's * all existing action->thread_mask bits. */ - new->thread_mask = 1 << ffz(thread_mask); + new->thread_mask = 1UL << ffz(thread_mask); } else if (new->handler == irq_default_primary_handler && !(desc->irq_data.chip->flags & IRQCHIP_ONESHOT_SAFE)) { |