From 4755200b6b116dbf6d5545427e8a2cf58194ba6b Mon Sep 17 00:00:00 2001 From: Nicolas Pitre Date: Wed, 16 Aug 2017 16:05:13 -0400 Subject: binfmt_elf: don't attempt to load FDPIC binaries On platforms where both ELF and ELF-FDPIC variants are available, the regular ELF loader will happily identify FDPIC binaries as proper ELF and load them without the necessary FDPIC fixups, resulting in an immediate user space crash. Let's prevent binflt_elf from loading those binaries so binfmt_elf_fdpic has a chance to pick them up. For those architectures that don't define elf_check_fdpic(), a default version returning false is provided. Signed-off-by: Nicolas Pitre Acked-by: Mickael GUENE Tested-by: Vincent Abriou Tested-by: Andras Szemzo --- fs/binfmt_elf.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) (limited to 'fs/binfmt_elf.c') diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index 6466153f2bf0..89536811d8f8 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -51,6 +51,11 @@ #define user_siginfo_t siginfo_t #endif +/* That's for binfmt_elf_fdpic to deal with */ +#ifndef elf_check_fdpic +#define elf_check_fdpic(ex) false +#endif + static int load_elf_binary(struct linux_binprm *bprm); static unsigned long elf_map(struct file *, unsigned long, struct elf_phdr *, int, int, unsigned long); @@ -541,7 +546,8 @@ static unsigned long load_elf_interp(struct elfhdr *interp_elf_ex, if (interp_elf_ex->e_type != ET_EXEC && interp_elf_ex->e_type != ET_DYN) goto out; - if (!elf_check_arch(interp_elf_ex)) + if (!elf_check_arch(interp_elf_ex) || + elf_check_fdpic(interp_elf_ex)) goto out; if (!interpreter->f_op->mmap) goto out; @@ -717,6 +723,8 @@ static int load_elf_binary(struct linux_binprm *bprm) goto out; if (!elf_check_arch(&loc->elf_ex)) goto out; + if (elf_check_fdpic(&loc->elf_ex)) + goto out; if (!bprm->file->f_op->mmap) goto out; @@ -816,7 +824,8 @@ static int load_elf_binary(struct linux_binprm *bprm) if (memcmp(loc->interp_elf_ex.e_ident, ELFMAG, SELFMAG) != 0) goto out_free_dentry; /* Verify the interpreter has a valid arch */ - if (!elf_check_arch(&loc->interp_elf_ex)) + if (!elf_check_arch(&loc->interp_elf_ex) || + elf_check_fdpic(&loc->interp_elf_ex)) goto out_free_dentry; /* Load the interpreter program headers */ @@ -1188,6 +1197,8 @@ static int load_elf_library(struct file *file) if (elf_ex.e_type != ET_EXEC || elf_ex.e_phnum > 2 || !elf_check_arch(&elf_ex) || !file->f_op->mmap) goto out; + if (elf_check_fdpic(&elf_ex)) + goto out; /* Now read in all of the header information */ -- cgit v1.2.3-55-g7522