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| author | peterz@infradead.org <peterz@infradead.org> | 2023-09-21 12:45:09 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2023-09-21 19:22:06 +0200 |
| commit | 698eb826383616ce0e817d2384da6413d1439fb6 (patch) | |
| tree | bd22f2fa7f6a8a57253b9040778f5d12f5c43228 | |
| parent | 5694289ce183bc3336407a78c8c722a0b9208f9b (diff) | |
| download | linux-stable-698eb826383616ce0e817d2384da6413d1439fb6.tar.gz linux-stable-698eb826383616ce0e817d2384da6413d1439fb6.tar.bz2 linux-stable-698eb826383616ce0e817d2384da6413d1439fb6.zip | |
futex: Validate futex value against futex size
Ensure the futex value fits in the given futex size. Since this adds a
constraint to an existing syscall, it might possibly change behaviour.
Currently the value would be truncated to a u32 and any high bits
would get silently lost.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20230921105247.828934099@noisy.programming.kicks-ass.net
| -rw-r--r-- | kernel/futex/futex.h | 10 | ||||
| -rw-r--r-- | kernel/futex/syscalls.c | 3 |
2 files changed, 13 insertions, 0 deletions
diff --git a/kernel/futex/futex.h b/kernel/futex/futex.h index 68fc052dc09b..a3f1fceafcbe 100644 --- a/kernel/futex/futex.h +++ b/kernel/futex/futex.h @@ -85,6 +85,16 @@ static inline bool futex_flags_valid(unsigned int flags) return true; } +static inline bool futex_validate_input(unsigned int flags, u64 val) +{ + int bits = 8 * futex_size(flags); + + if (bits < 64 && (val >> bits)) + return false; + + return true; +} + #ifdef CONFIG_FAIL_FUTEX extern bool should_fail_futex(bool fshared); #else diff --git a/kernel/futex/syscalls.c b/kernel/futex/syscalls.c index 948ac247c1c6..2339f9ccee7f 100644 --- a/kernel/futex/syscalls.c +++ b/kernel/futex/syscalls.c @@ -209,6 +209,9 @@ static int futex_parse_waitv(struct futex_vector *futexv, if (!futex_flags_valid(flags)) return -EINVAL; + if (!futex_validate_input(flags, aux.val)) + return -EINVAL; + futexv[i].w.flags = flags; futexv[i].w.val = aux.val; futexv[i].w.uaddr = aux.uaddr; |