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RCPT_COUNT_SEVEN(0.00)[7]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; RECEIVED_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:106:10:150:64:167:received]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.com:url,imap1.dmz-prg2.suse.org:helo,imap1.dmz-prg2.suse.org:rdns] X-Rspamd-Queue-Id: 357316A989 X-Spam-Flag: NO X-Spam-Score: -4.51 X-Spam-Level: Am 09.04.26 um 18:41 schrieb Ashutosh Desai: > drm_gem_fb_init_with_funcs() computes sub-sampled plane dimensions > using plain integer division: > > unsigned int width = mode_cmd->width / (i ? info->hsub : 1); > unsigned int height = mode_cmd->height / (i ? info->vsub : 1); > > However, the ioctl-level framebuffer_check() in drm_framebuffer.c uses > drm_format_info_plane_width/height() which round up dimensions via > DIV_ROUND_UP(). This inconsistency corrupts the subsequent GEM object > size check for certain pixel format and dimension combinations. > > For example, with NV12 (vsub=2) and a 1-pixel-tall framebuffer the > GEM size validation path sees height=0 instead of height=1. The > expression (height - 1) then wraps to UINT_MAX as an unsigned int, > causing min_size to overflow and wrap back to a small value. A tiny > GEM object therefore passes the size guard, yet when the GPU accesses > the chroma plane it will read or write memory beyond the object's > bounds. > > Fix by replacing the open-coded divisions with drm_format_info_plane_width() > and drm_format_info_plane_height(), which use DIV_ROUND_UP() and match > the calculation already used in framebuffer_check(). > > Signed-off-by: Ashutosh Desai Thanks for the fix. Reviewed-by: Thomas Zimmermann Fixes: 4c3dbb2c312c ("drm: Add GEM backed framebuffer library") Cc: # v4.14+ > --- > drivers/gpu/drm/drm_gem_framebuffer_helper.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/drm_gem_framebuffer_helper.c b/drivers/gpu/drm/drm_gem_framebuffer_helper.c > index 9166c353f..88808e972 100644 > --- a/drivers/gpu/drm/drm_gem_framebuffer_helper.c > +++ b/drivers/gpu/drm/drm_gem_framebuffer_helper.c > @@ -172,8 +172,8 @@ int drm_gem_fb_init_with_funcs(struct drm_device *dev, > } > > for (i = 0; i < info->num_planes; i++) { > - unsigned int width = mode_cmd->width / (i ? info->hsub : 1); > - unsigned int height = mode_cmd->height / (i ? info->vsub : 1); > + unsigned int width = drm_format_info_plane_width(info, mode_cmd->width, i); > + unsigned int height = drm_format_info_plane_height(info, mode_cmd->height, i); > unsigned int min_size; > > objs[i] = drm_gem_object_lookup(file, mode_cmd->handles[i]); -- -- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG Nürnberg)