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author | Pavel Emelyanov <xemul@openvz.org> | 2008-04-29 00:59:24 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-04-29 08:06:04 -0700 |
commit | 3a2e7f47d71e1df86acc1dda6826890b6546a4e1 (patch) | |
tree | 3c5856f67af25a80a4d934e754f437936c7b1bbf /fs/binfmt_misc.c | |
parent | cbd9b67bd3883dff0ef4b8ec9229d315a9ba38f0 (diff) | |
download | kernel_samsung_aries-3a2e7f47d71e1df86acc1dda6826890b6546a4e1.zip kernel_samsung_aries-3a2e7f47d71e1df86acc1dda6826890b6546a4e1.tar.gz kernel_samsung_aries-3a2e7f47d71e1df86acc1dda6826890b6546a4e1.tar.bz2 |
binfmt_misc.c: avoid potential kernel stack overflow
This can be triggered with root help only, but...
Register the ":text:E::txt::/root/cat.txt:' rule in binfmt_misc (by root) and
try launching the cat.txt file (by anyone) :) The result is - the endless
recursion in the load_misc_binary -> open_exec -> load_misc_binary chain and
stack overflow.
There's a similar problem with binfmt_script, and there's a sh_bang memner on
linux_binprm structure to handle this, but simply raising this in binfmt_misc
may break some setups when the interpreter of some misc binaries is a script.
So the proposal is to turn sh_bang into a bit, add a new one (the misc_bang)
and raise it in load_misc_binary. After this, even if we set up the misc ->
script -> misc loop for binfmts one of them will step on its own bang and
exit.
Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/binfmt_misc.c')
-rw-r--r-- | fs/binfmt_misc.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/fs/binfmt_misc.c b/fs/binfmt_misc.c index dbf0ac0..7191306 100644 --- a/fs/binfmt_misc.c +++ b/fs/binfmt_misc.c @@ -115,6 +115,12 @@ static int load_misc_binary(struct linux_binprm *bprm, struct pt_regs *regs) if (!enabled) goto _ret; + retval = -ENOEXEC; + if (bprm->misc_bang) + goto _ret; + + bprm->misc_bang = 1; + /* to keep locking time low, we copy the interpreter string */ read_lock(&entries_lock); fmt = check_file(bprm); |