[PATCH 6.12 143/144] drm/amdgpu/vcn3: Avoid overflow on msg bound check

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

6.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Benjamin Cheng <benjamin.cheng@amd.com>

commit e6e9faba8100628990cccd13f0f044a648c303cf upstream.

As pointed out by SDL, the previous condition may be vulnerable to
overflow.

Fixes: b193019860d6 ("drm/amdgpu/vcn3: Prevent OOB reads when parsing dec msg")
Cc: SDL <sdl@nppct.ru>
Signed-off-by: Benjamin Cheng <benjamin.cheng@amd.com>
Reviewed-by: Ruijing Dong <ruijing.dong@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit db00257ac9e4a51eb2515aaea161a019f7125e10)
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/gpu/drm/amd/amdgpu/vcn_v3_0.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/gpu/drm/amd/amdgpu/vcn_v3_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/vcn_v3_0.c
@@ -1906,6 +1906,7 @@ static int vcn_v3_0_dec_msg(struct amdgp
 
 	for (i = 0, msg = &msg[6]; i < num_buffers; ++i, msg += 4) {
 		uint32_t offset, size, *create;
+		uint64_t buf_end;
 
 		if (msg[0] != RDECODE_MESSAGE_CREATE)
 			continue;
@@ -1913,7 +1914,8 @@ static int vcn_v3_0_dec_msg(struct amdgp
 		offset = msg[1];
 		size = msg[2];
 
-		if (size < 4 || offset + size > end - addr) {
+		if (size < 4 || check_add_overflow(offset, size, &buf_end) ||
+		    buf_end > end - addr) {
 			DRM_ERROR("VCN message buffer exceeds BO bounds!\n");
 			r = -EINVAL;
 			goto out;