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authorNicolas Pitre <nicolas.pitre@linaro.org>2017-08-16 16:05:13 -0400
committerNicolas Pitre <nicolas.pitre@linaro.org>2017-09-10 19:31:47 -0400
commit4755200b6b116dbf6d5545427e8a2cf58194ba6b (patch)
tree68886d0d774a06af916967474c7ecc45dde201bd
parent382e67aec6a7eea8ed4403e86950b468a191c468 (diff)
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 <nico@linaro.org> Acked-by: Mickael GUENE <mickael.guene@st.com> Tested-by: Vincent Abriou <vincent.abriou@st.com> Tested-by: Andras Szemzo <szemzo.andras@gmail.com>
-rw-r--r--fs/binfmt_elf.c15
1 files changed, 13 insertions, 2 deletions
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 */