From: Jiri Kosina Date: Wed, 2 Nov 2011 20:37:41 +0000 (-0700) Subject: binfmt_elf: fix PIE execution with randomization disabled X-Git-Tag: firefly_0821_release~3680^2~4226^2~49 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=a3defbe5c337;p=firefly-linux-kernel-4.4.55.git binfmt_elf: fix PIE execution with randomization disabled The case of address space randomization being disabled in runtime through randomize_va_space sysctl is not treated properly in load_elf_binary(), resulting in SIGKILL coming at exec() time for certain PIE-linked binaries in case the randomization has been disabled at runtime prior to calling exec(). Handle the randomize_va_space == 0 case the same way as if we were not supporting .text randomization at all. Based on original patch by H.J. Lu and Josh Boyer. Signed-off-by: Jiri Kosina Cc: Ingo Molnar Cc: Russell King Cc: H.J. Lu Cc: Tested-by: Josh Boyer Acked-by: Nicolas Pitre Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index dd0fdfc56d38..21ac5ee4b43f 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -795,7 +795,16 @@ static int load_elf_binary(struct linux_binprm *bprm, struct pt_regs *regs) * might try to exec. This is because the brk will * follow the loader, and is not movable. */ #if defined(CONFIG_X86) || defined(CONFIG_ARM) - load_bias = 0; + /* Memory randomization might have been switched off + * in runtime via sysctl. + * If that is the case, retain the original non-zero + * load_bias value in order to establish proper + * non-randomized mappings. + */ + if (current->flags & PF_RANDOMIZE) + load_bias = 0; + else + load_bias = ELF_PAGESTART(ELF_ET_DYN_BASE - vaddr); #else load_bias = ELF_PAGESTART(ELF_ET_DYN_BASE - vaddr); #endif