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exec: kill "int depth" in search_binary_handler() 

Nobody except search_binary_handler() should touch ->recursion_depth, "int
depth" buys nothing but complicates the code, kill it.

Probably we should also kill "fn" and the !NULL check, ->load_binary
should be always defined.  And it can not go away after read_unlock() or
this code is buggy anyway.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Evgeniy Polyakov <zbr@ioremap.net>
Cc: Zach Levis <zml@linux.vnet.ibm.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 2013-09-11 14:24:39 -07:00 committed by Linus Torvalds
parent 5d1baf3b63
commit 131b2f9f12
2 changed files with 5 additions and 6 deletions
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9
fs/exec.c
View File

@ -1370,12 +1370,11 @@ EXPORT_SYMBOL(remove_arg_zero);
*/
int search_binary_handler(struct linux_binprm *bprm)
{
unsigned int depth = bprm->recursion_depth;
int try,retval;
int try, retval;
struct linux_binfmt *fmt;
/* This allows 4 levels of binfmt rewrites before failing hard. */
if (depth > 5)
if (bprm->recursion_depth > 5)
return -ELOOP;
retval = security_bprm_check(bprm);
@ -1396,9 +1395,9 @@ int search_binary_handler(struct linux_binprm *bprm)
if (!try_module_get(fmt->module))
continue;
read_unlock(&binfmt_lock);
bprm->recursion_depth = depth + 1;
bprm->recursion_depth++;
retval = fn(bprm);
bprm->recursion_depth = depth;
bprm->recursion_depth--;
if (retval >= 0) {
put_binfmt(fmt);
allow_write_access(bprm->file);

2
include/linux/binfmts.h
View File

@ -31,7 +31,7 @@ struct linux_binprm {
#ifdef __alpha__
unsigned int taso:1;
#endif
unsigned int recursion_depth;
unsigned int recursion_depth; /* only for search_binary_handler() */
struct file * file;
struct cred *cred; /* new credentials */
int unsafe; /* how unsafe this exec is (mask of LSM_UNSAFE_*) */