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s390/archrandom: add parameter check for s390_arch_random_generate
[ Upstream commit 2809606768
]
A review of the code showed, that this function which is exposed
within the whole kernel should do a parameter check for the
amount of bytes requested. If this requested bytes is too high
an unsigned int overflow could happen causing this function to
try to memcpy a really big memory chunk.
This is not a security issue as there are only two invocations
of this function from arch/s390/include/asm/archrandom.h and both
are not exposed to userland.
Reported-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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@ -53,6 +53,10 @@ static DECLARE_DELAYED_WORK(arch_rng_work, arch_rng_refill_buffer);
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bool s390_arch_random_generate(u8 *buf, unsigned int nbytes)
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{
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/* max hunk is ARCH_RNG_BUF_SIZE */
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if (nbytes > ARCH_RNG_BUF_SIZE)
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return false;
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/* lock rng buffer */
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if (!spin_trylock(&arch_rng_lock))
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return false;
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