diff options
author | Petr Písař <ppisar@redhat.com> | 2019-06-11 06:28:12 -0700 |
---|---|---|
committer | Wim Taymans <wtaymans@redhat.com> | 2020-02-14 13:02:29 +0100 |
commit | 1423e12e0bcf5cc43804ac5b31156a4acc316ea9 (patch) | |
tree | 8daeddd121eac9e00ed7deb8e6f07e82a04199c0 | |
parent | 5cf68a3fbb846da51e1b867e3fd92ec8d0e7a0dd (diff) |
CVE-2019-7635: Reject BMP images with pixel colors out the palette
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.
CVE-2019-7635
https://bugzilla.libsdl.org/show_bug.cgi?id=4498
Signed-off-by: Petr Písař <ppisar@redhat.com>
--HG--
branch : SDL-1.2
-rw-r--r-- | src/video/SDL_bmp.c | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/src/video/SDL_bmp.c b/src/video/SDL_bmp.c index 1b6e0ed060..c1f1a24f5c 100644 --- a/src/video/SDL_bmp.c +++ b/src/video/SDL_bmp.c @@ -301,6 +301,12 @@ 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; @@ -311,6 +317,16 @@ 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; i<surface->w; ++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. */ |