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由 Greg Kurz 提交于
The add_early_randomness() function in drivers/char/hw_random/core.c passes a 16-byte buffer to pseries_rng_data_read(). Unfortunately, plpar_hcall() returns four 64-bit values and trashes 16 bytes on the stack. This bug has been lying around for a long time. It got unveiled by: commit d3cc7996 Author: Amit Shah <amit.shah@redhat.com> Date: Thu Jul 10 15:42:34 2014 +0530 hwrng: fetch randomness only after device init It may trig a oops while loading or unloading the pseries-rng module for both PowerVM and PowerKVM guests. This patch does two things: - pass an intermediate well sized buffer to plpar_hcall(). This is acceptalbe since we're not on a hot path. - move to the new read API so that we know the return buffer size for sure. Cc: stable@vger.kernel.org Signed-off-by: NGreg Kurz <gkurz@linux.vnet.ibm.com> Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>
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