From: =?utf-8?b?UGV0ciBQw61zYcWZ?= Date: Tue, 11 Jun 2019 06:28:12 -0700 Subject: CVE-2019-7635: Reject BMP images with pixel colors out the palette MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit If a 1-, 4-, or 8-bit per pixel BMP image declares less used colors than the palette offers an SDL_Surface with a palette of the indicated number of used colors is created. If some of the image's pixel refer to a color number higher then the maximal used colors, a subsequent bliting operation on the surface will look up a color past a blit map (that is based on the palette) memory. I.e. passing such SDL_Surface to e.g. an SDL_DisplayFormat() function will result in a buffer overread in a blit function. This patch fixes it by validing each pixel's color to be less than the maximal color number in the palette. A validation failure raises an error from a SDL_LoadBMP_RW() function. Bug: https://bugzilla.libsdl.org/show_bug.cgi?id=4498 Bug-CVE: CVE-2019-7635 Signed-off-by: Petr Písař Origin: upstream, commit:https://github.com/libsdl-org/SDL-1.2/commit/32c57bf53b18dafb7298d6e9113632728e8fe1ba --- src/video/SDL_bmp.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/src/video/SDL_bmp.c b/src/video/SDL_bmp.c index da4e4ab..758d4bb 100644 --- a/src/video/SDL_bmp.c +++ b/src/video/SDL_bmp.c @@ -308,6 +308,12 @@ SDL_Surface * SDL_LoadBMP_RW (SDL_RWops *src, int freesrc) } *(bits+i) = (pixel>>shift); pixel <<= ExpandBMP; + if ( bits[i] >= biClrUsed ) { + SDL_SetError( + "A BMP image contains a pixel with a color out of the palette"); + was_error = SDL_TRUE; + goto done; + } } } break; @@ -318,6 +324,16 @@ SDL_Surface * SDL_LoadBMP_RW (SDL_RWops *src, int freesrc) was_error = SDL_TRUE; goto done; } + if ( 8 == biBitCount && palette && biClrUsed < (1 << biBitCount ) ) { + for ( i=0; iw; ++i ) { + if ( bits[i] >= biClrUsed ) { + SDL_SetError( + "A BMP image contains a pixel with a color out of the palette"); + was_error = SDL_TRUE; + goto done; + } + } + } #if SDL_BYTEORDER == SDL_BIG_ENDIAN /* Byte-swap the pixels if needed. Note that the 24bpp case has already been taken care of above. */