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From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
To: linux-efi@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	"H . Peter Anvin" <hpa@zytor.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	linux-kernel@vger.kernel.org,
	Matt Fleming <matt@codeblueprint.co.uk>
Subject: [PATCH 1/2] efi/efi_test: Prevent an Oops in efi_runtime_query_capsulecaps()
Date: Wed, 25 Oct 2017 11:04:47 +0100	[thread overview]
Message-ID: <20171025100448.26056-2-ard.biesheuvel@linaro.org> (raw)
In-Reply-To: <20171025100448.26056-1-ard.biesheuvel@linaro.org>

From: Dan Carpenter <dan.carpenter@oracle.com>

If "qcaps.capsule_count" is ULONG_MAX then "qcaps.capsule_count + 1"
will overflow to zero and kcalloc() will return the ZERO_SIZE_PTR.  We
try to dereference it inside the loop and crash.

Fixes: ff6301dabc3c ("efi: Add efi_test driver for exporting UEFI runtime service interfaces")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Ivan Hu <ivan.hu@canonical.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 drivers/firmware/efi/test/efi_test.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/firmware/efi/test/efi_test.c b/drivers/firmware/efi/test/efi_test.c
index 08129b7b80ab..41c48a1e8baa 100644
--- a/drivers/firmware/efi/test/efi_test.c
+++ b/drivers/firmware/efi/test/efi_test.c
@@ -593,6 +593,9 @@ static long efi_runtime_query_capsulecaps(unsigned long arg)
 	if (copy_from_user(&qcaps, qcaps_user, sizeof(qcaps)))
 		return -EFAULT;
 
+	if (qcaps.capsule_count == ULONG_MAX)
+		return -EINVAL;
+
 	capsules = kcalloc(qcaps.capsule_count + 1,
 			   sizeof(efi_capsule_header_t), GFP_KERNEL);
 	if (!capsules)
-- 
2.11.0

  reply	other threads:[~2017-10-25 10:09 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-10-25 10:04 [GIT PULL 0/2] EFI fixes for v4.14 Ard Biesheuvel
2017-10-25 10:04 ` Ard Biesheuvel
2017-10-25 10:04 ` Ard Biesheuvel [this message]
2017-10-25 11:09   ` [tip:efi/urgent] efi/efi_test: Prevent an Oops in efi_runtime_query_capsulecaps() tip-bot for Dan Carpenter
2017-10-25 10:04 ` [PATCH 2/2] efi/libstub: arm: don't randomize runtime regions when CONFIG_HIBERNATION=y Ard Biesheuvel
2017-10-25 11:10   ` [tip:efi/urgent] efi/libstub/arm: Don't " tip-bot for Ard Biesheuvel

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