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| author | Michael Ellerman <mpe@ellerman.id.au> | 2022-07-28 00:32:17 +1000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-08-17 14:22:58 +0200 |
| commit | db68d474cf096dd0a328386ee018f1023e09f21d (patch) | |
| tree | c76afeb39d471cf7201e9dd6651ea74214160963 /arch/powerpc/platforms | |
| parent | 552a29e47174f49bc47c7031162b79a16d40303c (diff) | |
| download | linux-stable-db68d474cf096dd0a328386ee018f1023e09f21d.tar.gz linux-stable-db68d474cf096dd0a328386ee018f1023e09f21d.tar.bz2 linux-stable-db68d474cf096dd0a328386ee018f1023e09f21d.zip | |
powerpc/powernv: Avoid crashing if rng is NULL
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: e928e9cb3601 ("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>
Diffstat (limited to 'arch/powerpc/platforms')
| -rw-r--r-- | arch/powerpc/platforms/powernv/rng.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/powerpc/platforms/powernv/rng.c b/arch/powerpc/platforms/powernv/rng.c index 236bd2ba51b9..a99033c3dce7 100644 --- a/arch/powerpc/platforms/powernv/rng.c +++ b/arch/powerpc/platforms/powernv/rng.c @@ -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)); |