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| author | Oleg Nesterov <oleg@redhat.com> | 2019-01-03 15:28:07 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-02-20 10:13:14 +0100 |
| commit | 9a376109f0c3b78d56adeb2134d4f2cb2a765ce9 (patch) | |
| tree | a678471bfb4771e3f075bd87684a37a0dfdbbfb7 | |
| parent | e1d575b52c32b40184c1d1ca6039e8c7d3ce2db7 (diff) | |
| download | linux-rt-9a376109f0c3b78d56adeb2134d4f2cb2a765ce9.tar.gz | |
exec: load_script: don't blindly truncate shebang string
[ Upstream commit 8099b047ecc431518b9bb6bdbba3549bbecdc343 ]
load_script() simply truncates bprm->buf and this is very wrong if the
length of shebang string exceeds BINPRM_BUF_SIZE-2. This can silently
truncate i_arg or (worse) we can execute the wrong binary if buf[2:126]
happens to be the valid executable path.
Change load_script() to return ENOEXEC if it can't find '\n' or zero in
bprm->buf. Note that '\0' can come from either
prepare_binprm()->memset() or from kernel_read(), we do not care.
Link: http://lkml.kernel.org/r/20181112160931.GA28463@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Ben Woodard <woodard@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | fs/binfmt_script.c | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/fs/binfmt_script.c b/fs/binfmt_script.c index afdf4e3cafc2..634bdbb23851 100644 --- a/fs/binfmt_script.c +++ b/fs/binfmt_script.c @@ -43,10 +43,14 @@ static int load_script(struct linux_binprm *bprm) fput(bprm->file); bprm->file = NULL; - bprm->buf[BINPRM_BUF_SIZE - 1] = '\0'; - if ((cp = strchr(bprm->buf, '\n')) == NULL) - cp = bprm->buf+BINPRM_BUF_SIZE-1; + for (cp = bprm->buf+2;; cp++) { + if (cp >= bprm->buf + BINPRM_BUF_SIZE) + return -ENOEXEC; + if (!*cp || (*cp == '\n')) + break; + } *cp = '\0'; + while (cp > bprm->buf) { cp--; if ((*cp == ' ') || (*cp == '\t')) |