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author | Rasmus Villemoes <linux@rasmusvillemoes.dk> | 2017-10-30 22:35:47 +0100 |
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committer | Thomas Gleixner <tglx@linutronix.de> | 2017-11-12 23:25:40 +0100 |
commit | ffc661c99f621152d5fdcf53f9df0d48c326318b (patch) | |
tree | 541eeda902b4a35a7fab7fd92cdf9691a3e691f1 /Documentation/devicetree/bindings/interrupt-controller/arm,gic-v3.txt | |
parent | 306eb5a38dfc1a4c8a5c910c9844da6a97f2b9a4 (diff) | |
download | op-kernel-dev-ffc661c99f621152d5fdcf53f9df0d48c326318b.zip op-kernel-dev-ffc661c99f621152d5fdcf53f9df0d48c326318b.tar.gz |
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
Diffstat (limited to 'Documentation/devicetree/bindings/interrupt-controller/arm,gic-v3.txt')
0 files changed, 0 insertions, 0 deletions