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exec: load_script: kill the onstack interp[BINPRM_BUF_SIZE] array

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Patch series "exec: binfmt_misc: fix use-after-free, kill
iname[BINPRM_BUF_SIZE]".

It looks like this code was always wrong, then commit 948b701a60
("binfmt_misc: add persistent opened binary handler for containers")
added more problems.

This patch (of 6):

load_script() can simply use i_name instead, it points into bprm->buf[]
and nobody can change this memory until we call prepare_binprm().

The only complication is that we need to also change the signature of
bprm_change_interp() but this change looks good too.

While at it, do whitespace/style cleanups.

NOTE: the real motivation for this change is that people want to
increase BINPRM_BUF_SIZE, we need to change load_misc_binary() too but
this looks more complicated because afaics it is very buggy.

Link: http://lkml.kernel.org/r/20170918163446.GA26793@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Travis Gummels <tgummels@redhat.com>
Cc: Ben Woodard <woodard@redhat.com>
Cc: Jim Foraker <foraker1@llnl.gov>
Cc: <tdhooge@llnl.gov>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Oleg Nesterov
2017-10-03 16:15:42 -07:00
committed by Linus Torvalds
parent 384632e67e
commit c2315c187f
3 changed files with 11 additions and 10 deletions
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2
include/linux/binfmts.h
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@@ -131,7 +131,7 @@ extern int setup_arg_pages(struct linux_binprm * bprm,
int executable_stack);
extern int transfer_args_to_stack(struct linux_binprm *bprm,
unsigned long *sp_location);
extern int bprm_change_interp(char *interp, struct linux_binprm *bprm);
extern int bprm_change_interp(const char *interp, struct linux_binprm *bprm);
extern int copy_strings_kernel(int argc, const char *const *argv,
struct linux_binprm *bprm);
extern int prepare_bprm_creds(struct linux_binprm *bprm);