BTW, just as a followup, David Daney supposedly fixed this in the kernel: From: David Daney <[email protected]> Subject: [PATCH 1/2] MIPS: Quit clobbering personality bits. To: [email protected], [email protected] Cc: David Daney <[email protected]>, Camm Maguire <[email protected]> Date: Mon, 1 Nov 2010 17:43:07 -0700
The high bits of current->personality carry settings that we don't want to clobber on each exec. Only clobber them if the lower bits that indicate either PER_LINUX or PER_LINUX32 are invalid. The clobbering prevents us from using useful bits like ADDR_NO_RANDOMIZE. Reported-by: Camm Maguire <[email protected]> Signed-off-by: David Daney <[email protected]> Cc: Camm Maguire <[email protected]> --- arch/mips/include/asm/elf.h | 7 +++++-- 1 files changed, 5 insertions(+), 2 deletions(-) diff --git a/arch/mips/include/asm/elf.h b/arch/mips/include/asm/elf.h index fd1d39e..2ef5e82 100644 --- a/arch/mips/include/asm/elf.h +++ b/arch/mips/include/asm/elf.h @@ -249,7 +249,8 @@ extern struct mips_abi mips_abi_n32; #define SET_PERSONALITY(ex) \ do { \ - set_personality(PER_LINUX); \ + if (personality(current->personality) != PER_LINUX) \ + set_personality(PER_LINUX); \ \ current->thread.abi = &mips_abi; \ } while (0) @@ -296,6 +297,7 @@ do { \ #define SET_PERSONALITY(ex) \ do { \ + unsigned int p; \ clear_thread_flag(TIF_32BIT_REGS); \ clear_thread_flag(TIF_32BIT_ADDR); \ \ @@ -304,7 +306,8 @@ do { \ else \ current->thread.abi = &mips_abi; \ \ - if (current->personality != PER_LINUX32) \ + p = personality(current->personality); \ + if (p != PER_LINUX32 && p != PER_LINUX) \ set_personality(PER_LINUX); \ } while (0) -- 1.7.2.3 From: David Daney <[email protected]> Subject: [PATCH 2/2] MIPS: Don't clobber personality bits in 32-bit sys_personality(). To: [email protected], [email protected] Cc: David Daney <[email protected]>, Camm Maguire <[email protected]> Date: Mon, 1 Nov 2010 17:43:08 -0700 If PER_LINUX32 has been set on a 32-bit kernel, only twiddle with the low-order personality bits, let the upper bits pass through. Signed-off-by: David Daney <[email protected]> Cc: Camm Maguire <[email protected]> --- arch/mips/kernel/linux32.c | 12 ++++++------ 1 files changed, 6 insertions(+), 6 deletions(-) diff --git a/arch/mips/kernel/linux32.c b/arch/mips/kernel/linux32.c index 6343b4a..a63f4e2 100644 --- a/arch/mips/kernel/linux32.c +++ b/arch/mips/kernel/linux32.c @@ -252,13 +252,13 @@ SYSCALL_DEFINE5(n32_msgrcv, int, msqid, u32, msgp, size_t, msgsz, SYSCALL_DEFINE1(32_personality, unsigned long, personality) { int ret; - personality &= 0xffffffff; + unsigned int p = personality & 0xffffffff; if (personality(current->personality) == PER_LINUX32 && - personality == PER_LINUX) - personality = PER_LINUX32; - ret = sys_personality(personality); - if (ret == PER_LINUX32) - ret = PER_LINUX; + personality(p) == PER_LINUX) + p = (p & ~PER_MASK) | PER_LINUX32; + ret = sys_personality(p); + if (ret != -1 && personality(ret) == PER_LINUX32) + ret = (ret & ~PER_MASK) | PER_LINUX; return ret; } -- 1.7.2.3 Take care, Andreas Barth <[email protected]> writes: > * Camm Maguire ([email protected]) [101031 20:30]: >> Thanks so much! Any idea on what might have caused this recent >> failure on phrixos: >> >> checking for sbrk... yes >> checking for ADDR_NO_RANDOMIZE constant... yes, 40000 >> checking for personality(ADDR_NO_RANDOMIZE) support... yes >> checking that sbrk is (now) non-random... no >> Cannot build with randomized sbrk. Your options: >> - upgrade to a kernel/libc that knows about personality(ADDR_NO_RANDOMIZE) > > The output seems to indicate that ADDR_NO_RANDOMIZE is available? > >> - recompile your kernel with CONFIG_COMPAT_BRK (if it has that option) >> - run sysctl kernel.randomize_va_space=0 before using gcl >> >> gcl and dependencies re-exec with ADDR_NO_RANDOMIZE set to get >> traditional sbrk contiguous to the .data segment end. > > I upgraded to the Debian 2.6.36-rc6-loongson-2f kernel (the machine > runs now for the first time an default distribution kernel). That > might have some impact - I don't know. > > Also, kernel.randomize_va_space=2 currently. > > > > Andi > > > -- Camm Maguire [email protected] ========================================================================== "The earth is but one country, and mankind its citizens." -- Baha'u'llah -- To UNSUBSCRIBE, email to [email protected] with a subject of "unsubscribe". Trouble? Contact [email protected] Archive: http://lists.debian.org/[email protected]
