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Dotan Barak a écrit : > Hi all. > > I noticed that the code segment of the user level in PPC64 machines > is in a VMA with a write permission enabled. > > I'm using the following machine attributes: > ************************************************************* > Host Name : mtlsqt185 > Host Architecture : ppc64 > Linux Distribution: SUSE Linux Enterprise Server 10 (ppc) VERSION = 10 > PATCHLEVEL = 1 > Kernel Version : 2.6.16.53-0.16-ppc64 > GCC Version : gcc (GCC) 4.1.2 20070115 (prerelease) (SUSE Linux) > Memory size : 1740232 kB > Number of CPUs : 8 > cpu MHz : 4005.000000MHz > Driver Version : OFED-1.2.5.4-20071210-0614 > HCA ID(s) : mlx4_0 > HCA model(s) : 25418 > FW version(s) : 2.3.906 > Board(s) : IBM08A0000001 > ************************************************************* > > I printed the address of a function in my program and i got the value > 0x1005ac80. > > I printed the VMAs in my process and i got the following output: > mtlsqt185:~ # cat /proc/17366/maps > 00100000-00103000 r-xp 00100000 00:00 0 > 10000000-1004a000 r-xp 00000000 08:03 1063667 > /tmp/tsscr/svn.mlx_tp/branches/ofed1.2.5/gen2/userspace/useraccess/gen2_basic/gen2_basic > > 1005a000-1005e000 rw-p 0004a000 08:03 1063667 > /tmp/tsscr/svn.mlx_tp/branches/ofed1.2.5/gen2/userspace/useraccess/gen2_basic/gen2_basic > > 1005e000-1015f000 rw-p 1005e000 00:00 0 > [heap] > > Is this is a security hole (any virus can change the code in the code > segment ...) > > can you please CC me the answers o this question? > This is because on PPC architecture, address of a function points to a small data area (a function descriptor) where the caller can find informations about : - Address (in the text segment, so readonly) of the target function - Address of the TOC for this function. http://www.linux-foundation.org/spec/ELF/ppc64/PPC-elf64abi-1.9.html#FUNC-ADDRESS -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||||
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