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Add missing stack markings (non executable) #7

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merged 1 commit into from Sep 13, 2017

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@rverton
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rverton commented Jul 19, 2017

When playing with a default raspbian, @diouziou and I noticed that every stack, no matter if compiled with NX or not, is marked as executable.

➜  ~ cat /proc/self/maps
00010000-00019000 r-xp 00000000 b3:02 524        /bin/cat
00028000-00029000 r--p 00008000 b3:02 524        /bin/cat
00029000-0002a000 rw-p 00009000 b3:02 524        /bin/cat
00b8f000-00bb0000 rw-p 00000000 00:00 0          [heap]
76ac4000-76ae6000 rw-p 00000000 00:00 0 
76ae6000-76c17000 r--p 001c7000 b3:02 234        /usr/lib/locale/locale-archive
76c17000-76e17000 r--p 00000000 b3:02 234        /usr/lib/locale/locale-archive
76e17000-76f42000 r-xp 00000000 b3:02 1946       /lib/arm-linux-gnueabihf/libc-2.19.so
76f42000-76f52000 ---p 0012b000 b3:02 1946       /lib/arm-linux-gnueabihf/libc-2.19.so
76f52000-76f54000 r--p 0012b000 b3:02 1946       /lib/arm-linux-gnueabihf/libc-2.19.so
76f54000-76f55000 rw-p 0012d000 b3:02 1946       /lib/arm-linux-gnueabihf/libc-2.19.so
76f55000-76f58000 rw-p 00000000 00:00 0 
76f58000-76f5d000 r-xp 00000000 b3:02 10212      /usr/lib/arm-linux-gnueabihf/libarmmem.so
76f5d000-76f6c000 ---p 00005000 b3:02 10212      /usr/lib/arm-linux-gnueabihf/libarmmem.so
76f6c000-76f6d000 rw-p 00004000 b3:02 10212      /usr/lib/arm-linux-gnueabihf/libarmmem.so
76f6d000-76f8d000 r-xp 00000000 b3:02 1914       /lib/arm-linux-gnueabihf/ld-2.19.so
76f91000-76f93000 rw-p 00000000 00:00 0 
76f9a000-76f9c000 rw-p 00000000 00:00 0 
76f9c000-76f9d000 r--p 0001f000 b3:02 1914       /lib/arm-linux-gnueabihf/ld-2.19.so
76f9d000-76f9e000 rw-p 00020000 b3:02 1914       /lib/arm-linux-gnueabihf/ld-2.19.so
7ef24000-7ef45000 rwxp 00000000 00:00 0          [stack]
7eff4000-7eff5000 r-xp 00000000 00:00 0          [sigpage]
7eff5000-7eff6000 r--p 00000000 00:00 0          [vvar]
7eff6000-7eff7000 r-xp 00000000 00:00 0          [vdso]
ffff0000-ffff1000 r-xp 00000000 00:00 0          [vectors]

$ readelf -a /bin/cat | grep STACK
GNU_STACK      0x000000 0x00000000 0x00000000 0x00000 0x00000 RW  0x10

This is the same problem as with the old libcofi_rpi, where some stack markings where missing. The ASM lines to fix this are added to nearly all files in this lib, but not in architecture.S.

$ scanelf -e libarmmem.so 
 TYPE   STK/REL/PTL FILE 
ET_DYN RWX --- RW- libarmmem.so

This is for example responsible for nearly all binaries in raspbian to ignore NX. The fix will ensure that the correct stack markings are set.

$ scanelf -e libarmmem.so
 TYPE   STK/REL/PTL FILE 
ET_DYN RW- --- RW- libarmmem.so 

@bavison bavison merged commit c06d1f1 into bavison:master Sep 13, 2017

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bavison commented Sep 13, 2017

Good catch, thanks

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