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Fixed bug #855

 Ludwig Nussel      2009-10-18 06:31:52 PDT

an mprotect call was added to fix bug 528. However that results in a buffer
that allows writing and code execution. Ie the no-execute security features of
modern operating systems are defeated this way. Two mprotect calls are needed.
One to make the buffer executable but not writeable when done and another one
to make the buffer writeable again if the content needs to be changed.
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slouken committed Oct 18, 2009
1 parent a418ee0 commit 55d841880d9e3ef26348f520abca233edf0e5f10
Showing with 9 additions and 2 deletions.
  1. +9 −2 src/video/SDL_stretch.c
@@ -103,6 +103,13 @@ static int generate_rowbytes(int src_w, int dst_w, int bpp)
SDL_SetError("ASM stretch of %d bytes isn't supported\n", bpp);
return(-1);
}
#ifdef HAVE_MPROTECT
/* Make the code writeable */
if ( mprotect(copy_row, sizeof(copy_row), PROT_READ|PROT_WRITE) < 0 ) {
SDL_SetError("Couldn't make copy buffer writeable");
return(-1);
}
#endif
pos = 0x10000;
inc = (src_w << 16) / dst_w;
eip = copy_row;
@@ -128,8 +135,8 @@ static int generate_rowbytes(int src_w, int dst_w, int bpp)
return(-1);
}
#ifdef HAVE_MPROTECT
/* Make the code executable */
if ( mprotect(copy_row, sizeof(copy_row), PROT_READ|PROT_WRITE|PROT_EXEC) < 0 ) {
/* Make the code executable but not writeable */
if ( mprotect(copy_row, sizeof(copy_row), PROT_READ|PROT_EXEC) < 0 ) {
SDL_SetError("Couldn't make copy buffer executable");
return(-1);
}

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