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Allow recursion in binfmt_script and binfmt_misc

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binfmt_script and binfmt_misc disallow recursion to avoid stack overflow
using sh_bang and misc_bang.  It causes problem in some cases:

$ echo '#!/bin/ls' > /tmp/t0
$ echo '#!/tmp/t0' > /tmp/t1
$ echo '#!/tmp/t1' > /tmp/t2
$ chmod +x /tmp/t*
$ /tmp/t2
zsh: exec format error: /tmp/t2

Similar problem with binfmt_misc.

This patch introduces field 'recursion_depth' into struct linux_binprm to
track recursion level in binfmt_misc and binfmt_script.  If recursion
level more then BINPRM_MAX_RECURSION it generates -ENOEXEC.

[akpm@linux-foundation.org: make linux_binprm.recursion_depth a uint]
Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Kirill A. Shutemov
2008-10-15 22:02:39 -07:00
committed by Linus Torvalds
parent 53112488be
commit bf2a9a3963
4 changed files with 8 additions and 5 deletions
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2
include/linux/binfmts.h
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@@ -39,6 +39,7 @@ struct linux_binprm{
#ifdef __alpha__
unsigned int taso:1;
#endif
unsigned int recursion_depth;
struct file * file;
int e_uid, e_gid;
kernel_cap_t cap_post_exec_permitted;
@@ -61,6 +62,7 @@ struct linux_binprm{
#define BINPRM_FLAGS_EXECFD_BIT 1
#define BINPRM_FLAGS_EXECFD (1 << BINPRM_FLAGS_EXECFD_BIT)
#define BINPRM_MAX_RECURSION 4
/*
* This structure defines the functions that are used to load the binary formats that