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author | Kees Cook <keescook@chromium.org> | 2012-12-17 16:03:20 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-12-17 17:15:23 -0800 |
commit | d740269867021faf4ce38a449353d2b986c34a67 (patch) | |
tree | e0476e1be1dfb6e852adbaa8fb72ecea87bdb088 /fs/binfmt_em86.c | |
parent | 8d238027b87e654be552eabdf492042a34c5c300 (diff) | |
download | linux-d740269867021faf4ce38a449353d2b986c34a67.tar.gz |
exec: use -ELOOP for max recursion depth
To avoid an explosion of request_module calls on a chain of abusive scripts, fail maximum recursion with -ELOOP instead of -ENOEXEC. As soon as maximum recursion depth is hit, the error will fail all the way back up the chain, aborting immediately. This also has the side-effect of stopping the user's shell from attempting to reexecute the top-level file as a shell script. As seen in the dash source: if (cmd != path_bshell && errno == ENOEXEC) { *argv-- = cmd; *argv = cmd = path_bshell; goto repeat; } The above logic was designed for running scripts automatically that lacked the "#!" header, not to re-try failed recursion. On a legitimate -ENOEXEC, things continue to behave as the shell expects. Additionally, when tracking recursion, the binfmt handlers should not be involved. The recursion being tracked is the depth of calls through search_binary_handler(), so that function should be exclusively responsible for tracking the depth. Signed-off-by: Kees Cook <keescook@chromium.org> Cc: halfdog <me@halfdog.net> Cc: P J P <ppandit@redhat.com> 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>
Diffstat (limited to 'fs/binfmt_em86.c')
-rw-r--r-- | fs/binfmt_em86.c | 1 |
1 files changed, 0 insertions, 1 deletions
diff --git a/fs/binfmt_em86.c b/fs/binfmt_em86.c index 4e6cce57d113..037a3e2b045b 100644 --- a/fs/binfmt_em86.c +++ b/fs/binfmt_em86.c @@ -42,7 +42,6 @@ static int load_em86(struct linux_binprm *bprm) return -ENOEXEC; } - bprm->recursion_depth++; /* Well, the bang-shell is implicit... */ allow_write_access(bprm->file); fput(bprm->file); bprm->file = NULL; |