lisa/android_kernel_xiaomi_sm8350
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

powerpc/powernv: Avoid crashing if rng is NULL

Browse Source 
commit 90b5d4fe0b3ba7f589c6723c6bfb559d9e83956a upstream.

On a bare-metal Power8 system that doesn't have an "ibm,power-rng", a
malicious QEMU and guest that ignore the absence of the
KVM_CAP_PPC_HWRNG flag, and calls H_RANDOM anyway, will dereference a
NULL pointer.

In practice all Power8 machines have an "ibm,power-rng", but let's not
rely on that, add a NULL check and early return in
powernv_get_random_real_mode().

Fixes: e928e9cb36 ("KVM: PPC: Book3S HV: Add fast real-mode H_RANDOM implementation.")
Cc: stable@vger.kernel.org # v4.1+
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220727143219.2684192-1-mpe@ellerman.id.au
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Michael Ellerman 2022-07-28 00:32:17 +10:00 committed by Greg Kroah-Hartman
parent 5b8f55bc05
commit dbd0059018
1 changed files with 2 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/powerpc/platforms/powernv/rng.c
View File

@ -63,6 +63,8 @@ int powernv_get_random_real_mode(unsigned long *v)
struct powernv_rng *rng;
rng = raw_cpu_read(powernv_rng);
if (!rng)
return 0;
*v = rng_whiten(rng, __raw_rm_readq(rng->regs_real));