The patch titled
Allow recursion in binfmt_script and binfmt_misc
has been removed from the -mm tree. Its filename was
allow-recursion-in-binfmt_script-and-binfmt_misc.patch
This patch was dropped because it was merged into mainline or a subsystem tree
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: Allow recursion in binfmt_script and binfmt_misc
From: "Kirill A. Shutemov" <kirill@xxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxxxxxxx: make linux_binprm.recursion_depth a uint]
Signed-off-by: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx>
Cc: Pavel Emelyanov <xemul@xxxxxxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/binfmt_em86.c | 2 +-
fs/binfmt_misc.c | 4 ++--
fs/binfmt_script.c | 5 +++--
include/linux/binfmts.h | 2 ++
4 files changed, 8 insertions(+), 5 deletions(-)
diff -puN fs/binfmt_em86.c~allow-recursion-in-binfmt_script-and-binfmt_misc fs/binfmt_em86.c
--- a/fs/binfmt_em86.c~allow-recursion-in-binfmt_script-and-binfmt_misc
+++ a/fs/binfmt_em86.c
@@ -43,7 +43,7 @@ static int load_em86(struct linux_binprm
return -ENOEXEC;
}
- bprm->sh_bang = 1; /* Well, the bang-shell is implicit... */
+ bprm->recursion_depth++; /* Well, the bang-shell is implicit... */
allow_write_access(bprm->file);
fput(bprm->file);
bprm->file = NULL;
diff -puN fs/binfmt_misc.c~allow-recursion-in-binfmt_script-and-binfmt_misc fs/binfmt_misc.c
--- a/fs/binfmt_misc.c~allow-recursion-in-binfmt_script-and-binfmt_misc
+++ a/fs/binfmt_misc.c
@@ -117,7 +117,7 @@ static int load_misc_binary(struct linux
goto _ret;
retval = -ENOEXEC;
- if (bprm->misc_bang)
+ if (bprm->recursion_depth > BINPRM_MAX_RECURSION)
goto _ret;
/* to keep locking time low, we copy the interpreter string */
@@ -197,7 +197,7 @@ static int load_misc_binary(struct linux
if (retval < 0)
goto _error;
- bprm->misc_bang = 1;
+ bprm->recursion_depth++;
retval = search_binary_handler (bprm, regs);
if (retval < 0)
diff -puN fs/binfmt_script.c~allow-recursion-in-binfmt_script-and-binfmt_misc fs/binfmt_script.c
--- a/fs/binfmt_script.c~allow-recursion-in-binfmt_script-and-binfmt_misc
+++ a/fs/binfmt_script.c
@@ -22,14 +22,15 @@ static int load_script(struct linux_binp
char interp[BINPRM_BUF_SIZE];
int retval;
- if ((bprm->buf[0] != '#') || (bprm->buf[1] != '!') || (bprm->sh_bang))
+ if ((bprm->buf[0] != '#') || (bprm->buf[1] != '!') ||
+ (bprm->recursion_depth > BINPRM_MAX_RECURSION))
return -ENOEXEC;
/*
* This section does the #! interpretation.
* Sorta complicated, but hopefully it will work. -TYT
*/
- bprm->sh_bang = 1;
+ bprm->recursion_depth++;
allow_write_access(bprm->file);
fput(bprm->file);
bprm->file = NULL;
diff -puN include/linux/binfmts.h~allow-recursion-in-binfmt_script-and-binfmt_misc include/linux/binfmts.h
--- a/include/linux/binfmts.h~allow-recursion-in-binfmt_script-and-binfmt_misc
+++ a/include/linux/binfmts.h
@@ -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
_
Patches currently in -mm which might be from kirill@xxxxxxxxxxxxx are
origin.patch
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