diff options
| author | Michael Ellerman <mpe@ellerman.id.au> | 2022-07-27 17:32:17 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-08-21 16:15:26 +0300 |
| commit | 26d767990e160f38e5d9b1dcca79c88940c3804a (patch) | |
| tree | d654c036beb17ea563e9291eb1b3bce2e8126bdb | |
| parent | 3db593ab8e42144ba2d9067ad87d04bc7151a937 (diff) | |
| download | linux-26d767990e160f38e5d9b1dcca79c88940c3804a.tar.xz | |
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>
| -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)); |