[AMD Official Use Only - General]
From: SHANMUGAM, SRINIVASAN Sent: Tuesday, January 30, 2024 3:18 PM To: Siqueira, Rodrigo <rodrigo.sique...@amd.com>; Pillai, Aurabindo <aurabindo.pil...@amd.com> Cc: Cyr, Aric <aric....@amd.com>; amd-gfx@lists.freedesktop.org; Somasundaram, Meenakshikumar <meenakshikumar.somasunda...@amd.com>; Huang, PeiChen (Pei-Chen) <peichen.hu...@amd.com> Subject: Re: [PATCH] drm/amd/display: Fix buffer overflow in 'get_host_router_total_dp_tunnel_bw()' + Cc: Tom Chung <chiahsuan.ch...@amd.com<mailto:chiahsuan.ch...@amd.com>> On 1/29/2024 9:19 PM, Srinivasan Shanmugam wrote: The error message buffer overflow 'dc->links' 12 <= 12 suggests that the code is trying to access an element of the dc->links array that is beyond its bounds. In C, arrays are zero-indexed, so an array with 12 elements has valid indices from 0 to 11. Trying to access dc->links[12] would be an attempt to access the 13th element of a 12-element array, which is a buffer overflow. To fix this, ensure that the loop does not go beyond the last valid index when accessing dc->links[i + 1] by subtracting 1 from the loop condition. This would ensure that i + 1 is always a valid index in the array. Fixes the below: drivers/gpu/drm/amd/amdgpu/../display/dc/link/protocols/link_dp_dpia_bw.c:208 get_host_router_total_dp_tunnel_bw() error: buffer overflow 'dc->links' 12 <= 12 Fixes: 9ed0893b7c58 ("drm/amd/display: Add dpia display mode validation logic") Cc: PeiChen Huang <peichen.hu...@amd.com><mailto:peichen.hu...@amd.com> Cc: Aric Cyr <aric....@amd.com><mailto:aric....@amd.com> Cc: Rodrigo Siqueira <rodrigo.sique...@amd.com><mailto:rodrigo.sique...@amd.com> Cc: Aurabindo Pillai <aurabindo.pil...@amd.com><mailto:aurabindo.pil...@amd.com> Cc: Meenakshikumar Somasundaram <meenakshikumar.somasunda...@amd.com><mailto:meenakshikumar.somasunda...@amd.com> Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmu...@amd.com><mailto:srinivasan.shanmu...@amd.com> --- drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_dpia_bw.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_dpia_bw.c b/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_dpia_bw.c index dd0d2b206462..5491b707cec8 100644 --- a/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_dpia_bw.c +++ b/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_dpia_bw.c @@ -196,7 +196,7 @@ static int get_host_router_total_dp_tunnel_bw(const struct dc *dc, uint8_t hr_in struct dc_link *link_dpia_primary, *link_dpia_secondary; int total_bw = 0; - for (uint8_t i = 0; i < MAX_PIPES * 2; ++i) { + for (uint8_t i = 0; i < (MAX_PIPES * 2) - 1; ++i) { if (!dc->links[i] || dc->links[i]->ep_type != DISPLAY_ENDPOINT_USB4_DPIA) continue;
