From: Kees Cook Date: Thu, 26 Sep 2019 17:15:25 +0000 (-0700) Subject: binfmt_elf: Do not move brk for INTERP-less ET_EXEC X-Git-Tag: v5.2.19~64 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=89beb34d7533f778c3f04f948ee648a677e50a8c;p=thirdparty%2Fkernel%2Fstable.git binfmt_elf: Do not move brk for INTERP-less ET_EXEC commit 7be3cb019db1cbd5fd5ffe6d64a23fefa4b6f229 upstream. When brk was moved for binaries without an interpreter, it should have been limited to ET_DYN only. In other words, the special case was an ET_DYN that lacks an INTERP, not just an executable that lacks INTERP. The bug manifested for giant static executables, where the brk would end up in the middle of the text area on 32-bit architectures. Reported-and-tested-by: Richard Kojedzinszky Fixes: bbdc6076d2e5 ("binfmt_elf: move brk out of mmap when doing direct loader exec") Cc: stable@vger.kernel.org Signed-off-by: Kees Cook Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index 8264b468f2831..36d172ccb0850 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -1142,7 +1142,8 @@ out_free_interp: * (since it grows up, and may collide early with the stack * growing down), and into the unused ELF_ET_DYN_BASE region. */ - if (IS_ENABLED(CONFIG_ARCH_HAS_ELF_RANDOMIZE) && !interpreter) + if (IS_ENABLED(CONFIG_ARCH_HAS_ELF_RANDOMIZE) && + loc->elf_ex.e_type == ET_DYN && !interpreter) current->mm->brk = current->mm->start_brk = ELF_ET_DYN_BASE;