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Message-Id: <20230804093218.418276-1-shiftee@posteo.net>
Date: Fri, 4 Aug 2023 09:32:18 +0000
From: Mark O'Donovan <shiftee@...teo.net>
To: linux-kernel@...r.kernel.org
Cc: linux-crypto@...r.kernel.org, ebiggers@...gle.com,
herbert@...dor.apana.org.au, Mark O'Donovan <shiftee@...teo.net>
Subject: [PATCH RESEND] lib/mpi: avoid null pointer deref in mpi_cmp_ui()
During NVMeTCP Authentication a controller can trigger a kernel
oops by specifying the 8192 bit Diffie Hellman group and passing
a correctly sized, but zeroed Diffie Hellamn value.
mpi_cmp_ui() was detecting this if the second parameter was 0,
but 1 is passed from dh_is_pubkey_valid(). This causes the null
pointer u->d to be dereferenced towards the end of mpi_cmp_ui()
Signed-off-by: Mark O'Donovan <shiftee@...teo.net>
---
lib/mpi/mpi-cmp.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/lib/mpi/mpi-cmp.c b/lib/mpi/mpi-cmp.c
index c4cfa3ff0581..0835b6213235 100644
--- a/lib/mpi/mpi-cmp.c
+++ b/lib/mpi/mpi-cmp.c
@@ -25,8 +25,12 @@ int mpi_cmp_ui(MPI u, unsigned long v)
mpi_limb_t limb = v;
mpi_normalize(u);
- if (!u->nlimbs && !limb)
- return 0;
+ if (u->nlimbs == 0) {
+ if (v == 0)
+ return 0;
+ else
+ return -1;
+ }
if (u->sign)
return -1;
if (u->nlimbs > 1)
--
2.39.2
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