[tip: x86/urgent] x86/sgx: Add overflow check in sgx_validate_offset_length()

["tip-bot2 for Borys Popławski" <tip-bot2@linutronix.de>]

The following commit has been merged into the x86/urgent branch of tip:

Commit-ID:     f0861f49bd946ff94fce4f82509c45e167f63690
Gitweb:        https://git.kernel.org/tip/f0861f49bd946ff94fce4f82509c45e167f63690
Author:        Borys Popławski <borysp@invisiblethingslab.com>
AuthorDate:    Wed, 05 Oct 2022 00:59:03 +02:00
Committer:     Borislav Petkov <bp@suse.de>
CommitterDate: Tue, 08 Nov 2022 20:34:05 +01:00

x86/sgx: Add overflow check in sgx_validate_offset_length()

sgx_validate_offset_length() function verifies "offset" and "length"
arguments provided by userspace, but was missing an overflow check on
their addition. Add it.

Fixes: c6d26d370767 ("x86/sgx: Add SGX_IOC_ENCLAVE_ADD_PAGES")
Signed-off-by: Borys Popławski <borysp@invisiblethingslab.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Cc: stable@vger.kernel.org # v5.11+
Link: https://lore.kernel.org/r/0d91ac79-6d84-abed-5821-4dbe59fa1a38@invisiblethingslab.com
---
 arch/x86/kernel/cpu/sgx/ioctl.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c
index ebe79d6..da8b8ea 100644
--- a/arch/x86/kernel/cpu/sgx/ioctl.c
+++ b/arch/x86/kernel/cpu/sgx/ioctl.c
@@ -356,6 +356,9 @@ static int sgx_validate_offset_length(struct sgx_encl *encl,
 	if (!length || !IS_ALIGNED(length, PAGE_SIZE))
 		return -EINVAL;
 
+	if (offset + length < offset)
+		return -EINVAL;
+
 	if (offset + length - PAGE_SIZE >= encl->size)
 		return -EINVAL;