1# HG changeset patch 2# User Petr Písař <ppisar@redhat.com> 3# Date 1552788984 25200 4# Sat Mar 16 19:16:24 2019 -0700 5# Branch SDL-1.2 6# Node ID 9b0e5c555c0f5ce6d2c3c19da6cc2c7fb5048bf2 7# Parent 4646533663ae1d80c2cc6b2d6dbfb37c62491c1e 8CVE-2019-7637: Fix in integer overflow in SDL_CalculatePitch 9If a too large width is passed to SDL_SetVideoMode() the width travels 10to SDL_CalculatePitch() where the width (e.g. 65535) is multiplied by 11BytesPerPixel (e.g. 4) and the result is stored into Uint16 pitch 12variable. During this arithmetics an integer overflow can happen (e.g. 13the value is clamped as 65532). As a result SDL_Surface with a pitch 14smaller than width * BytesPerPixel is created, too small pixel buffer 15is allocated and when the SDL_Surface is processed in SDL_FillRect() 16a buffer overflow occurs. 17 18This can be reproduced with "./graywin -width 21312312313123213213213" 19command. 20 21This patch fixes is by using a very careful arithmetics in 22SDL_CalculatePitch(). If an overflow is detected, an error is reported 23back as a special 0 value. We assume that 0-width surfaces do not 24occur in the wild. Since SDL_CalculatePitch() is a private function, 25we can change the semantics. 26 27CVE-2019-7637 28https://bugzilla.libsdl.org/show_bug.cgi?id=4497 29 30Signed-off-by: Petr Písař <ppisar@redhat.com> 31 32CVE: CVE-2019-7637 33Upstream-Status: Backport 34Signed-off-by: Anuj Mittal <anuj.mittal@intel.com> 35 36diff -r 4646533663ae -r 9b0e5c555c0f src/video/SDL_pixels.c 37--- a/src/video/SDL_pixels.c Sat Mar 16 18:35:33 2019 -0700 38+++ b/src/video/SDL_pixels.c Sat Mar 16 19:16:24 2019 -0700 39@@ -286,26 +286,53 @@ 40 } 41 } 42 /* 43- * Calculate the pad-aligned scanline width of a surface 44+ * Calculate the pad-aligned scanline width of a surface. Return 0 in case of 45+ * an error. 46 */ 47 Uint16 SDL_CalculatePitch(SDL_Surface *surface) 48 { 49- Uint16 pitch; 50+ unsigned int pitch = 0; 51 52 /* Surface should be 4-byte aligned for speed */ 53- pitch = surface->w*surface->format->BytesPerPixel; 54+ /* The code tries to prevent from an Uint16 overflow. */; 55+ for (Uint8 byte = surface->format->BytesPerPixel; byte; byte--) { 56+ pitch += (unsigned int)surface->w; 57+ if (pitch < surface->w) { 58+ SDL_SetError("A scanline is too wide"); 59+ return(0); 60+ } 61+ } 62 switch (surface->format->BitsPerPixel) { 63 case 1: 64- pitch = (pitch+7)/8; 65+ if (pitch % 8) { 66+ pitch = pitch / 8 + 1; 67+ } else { 68+ pitch = pitch / 8; 69+ } 70 break; 71 case 4: 72- pitch = (pitch+1)/2; 73+ if (pitch % 2) { 74+ pitch = pitch / 2 + 1; 75+ } else { 76+ pitch = pitch / 2; 77+ } 78 break; 79 default: 80 break; 81 } 82- pitch = (pitch + 3) & ~3; /* 4-byte aligning */ 83- return(pitch); 84+ /* 4-byte aligning */ 85+ if (pitch & 3) { 86+ if (pitch + 3 < pitch) { 87+ SDL_SetError("A scanline is too wide"); 88+ return(0); 89+ } 90+ pitch = (pitch + 3) & ~3; 91+ } 92+ if (pitch > 0xFFFF) { 93+ SDL_SetError("A scanline is too wide"); 94+ return(0); 95+ } 96+ return((Uint16)pitch); 97 } 98 /* 99 * Match an RGB value to a particular palette index 100diff -r 4646533663ae -r 9b0e5c555c0f src/video/gapi/SDL_gapivideo.c 101--- a/src/video/gapi/SDL_gapivideo.c Sat Mar 16 18:35:33 2019 -0700 102+++ b/src/video/gapi/SDL_gapivideo.c Sat Mar 16 19:16:24 2019 -0700 103@@ -733,6 +733,9 @@ 104 video->w = gapi->w = width; 105 video->h = gapi->h = height; 106 video->pitch = SDL_CalculatePitch(video); 107+ if (!current->pitch) { 108+ return(NULL); 109+ } 110 111 /* Small fix for WinCE/Win32 - when activating window 112 SDL_VideoSurface is equal to zero, so activating code 113diff -r 4646533663ae -r 9b0e5c555c0f src/video/nanox/SDL_nxvideo.c 114--- a/src/video/nanox/SDL_nxvideo.c Sat Mar 16 18:35:33 2019 -0700 115+++ b/src/video/nanox/SDL_nxvideo.c Sat Mar 16 19:16:24 2019 -0700 116@@ -378,6 +378,10 @@ 117 current -> w = width ; 118 current -> h = height ; 119 current -> pitch = SDL_CalculatePitch (current) ; 120+ if (!current->pitch) { 121+ current = NULL; 122+ goto done; 123+ } 124 NX_ResizeImage (this, current, flags) ; 125 } 126 127diff -r 4646533663ae -r 9b0e5c555c0f src/video/ps2gs/SDL_gsvideo.c 128--- a/src/video/ps2gs/SDL_gsvideo.c Sat Mar 16 18:35:33 2019 -0700 129+++ b/src/video/ps2gs/SDL_gsvideo.c Sat Mar 16 19:16:24 2019 -0700 130@@ -479,6 +479,9 @@ 131 current->w = width; 132 current->h = height; 133 current->pitch = SDL_CalculatePitch(current); 134+ if (!current->pitch) { 135+ return(NULL); 136+ } 137 138 /* Memory map the DMA area for block memory transfer */ 139 if ( ! mapped_mem ) { 140diff -r 4646533663ae -r 9b0e5c555c0f src/video/ps3/SDL_ps3video.c 141--- a/src/video/ps3/SDL_ps3video.c Sat Mar 16 18:35:33 2019 -0700 142+++ b/src/video/ps3/SDL_ps3video.c Sat Mar 16 19:16:24 2019 -0700 143@@ -339,6 +339,9 @@ 144 current->w = width; 145 current->h = height; 146 current->pitch = SDL_CalculatePitch(current); 147+ if (!current->pitch) { 148+ return(NULL); 149+ } 150 151 /* Alloc aligned mem for current->pixels */ 152 s_pixels = memalign(16, current->h * current->pitch); 153diff -r 4646533663ae -r 9b0e5c555c0f src/video/windib/SDL_dibvideo.c 154--- a/src/video/windib/SDL_dibvideo.c Sat Mar 16 18:35:33 2019 -0700 155+++ b/src/video/windib/SDL_dibvideo.c Sat Mar 16 19:16:24 2019 -0700 156@@ -675,6 +675,9 @@ 157 video->w = width; 158 video->h = height; 159 video->pitch = SDL_CalculatePitch(video); 160+ if (!current->pitch) { 161+ return(NULL); 162+ } 163 164 /* Small fix for WinCE/Win32 - when activating window 165 SDL_VideoSurface is equal to zero, so activating code 166diff -r 4646533663ae -r 9b0e5c555c0f src/video/windx5/SDL_dx5video.c 167--- a/src/video/windx5/SDL_dx5video.c Sat Mar 16 18:35:33 2019 -0700 168+++ b/src/video/windx5/SDL_dx5video.c Sat Mar 16 19:16:24 2019 -0700 169@@ -1127,6 +1127,9 @@ 170 video->w = width; 171 video->h = height; 172 video->pitch = SDL_CalculatePitch(video); 173+ if (!current->pitch) { 174+ return(NULL); 175+ } 176 177 #ifndef NO_CHANGEDISPLAYSETTINGS 178 /* Set fullscreen mode if appropriate. 179diff -r 4646533663ae -r 9b0e5c555c0f src/video/x11/SDL_x11video.c 180--- a/src/video/x11/SDL_x11video.c Sat Mar 16 18:35:33 2019 -0700 181+++ b/src/video/x11/SDL_x11video.c Sat Mar 16 19:16:24 2019 -0700 182@@ -1225,6 +1225,10 @@ 183 current->w = width; 184 current->h = height; 185 current->pitch = SDL_CalculatePitch(current); 186+ if (!current->pitch) { 187+ current = NULL; 188+ goto done; 189+ } 190 if (X11_ResizeImage(this, current, flags) < 0) { 191 current = NULL; 192 goto done; 193