From 36c3e2f0890beda9deb9371490db25a537619adb Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Thu, 14 Feb 2019 15:02:18 -0800 Subject: [PATCH] Revert "exec: load_script: don't blindly truncate shebang string" commit cb5b020a8d38f77209d0472a0fea755299a8ec78 upstream. This reverts commit 8099b047ecc431518b9bb6bdbba3549bbecdc343. It turns out that people do actually depend on the shebang string being truncated, and on the fact that an interpreter (like perl) will often just re-interpret it entirely to get the full argument list. Reported-by: Samuel Dionne-Riel Acked-by: Kees Cook Cc: Oleg Nesterov Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- fs/binfmt_script.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) diff --git a/fs/binfmt_script.c b/fs/binfmt_script.c index f62e45df2d38a..5027a3e149222 100644 --- a/fs/binfmt_script.c +++ b/fs/binfmt_script.c @@ -33,14 +33,10 @@ static int load_script(struct linux_binprm *bprm) fput(bprm->file); bprm->file = NULL; - for (cp = bprm->buf+2;; cp++) { - if (cp >= bprm->buf + BINPRM_BUF_SIZE) - return -ENOEXEC; - if (!*cp || (*cp == '\n')) - break; - } + bprm->buf[BINPRM_BUF_SIZE - 1] = '\0'; + if ((cp = strchr(bprm->buf, '\n')) == NULL) + cp = bprm->buf+BINPRM_BUF_SIZE-1; *cp = '\0'; - while (cp > bprm->buf) { cp--; if ((*cp == ' ') || (*cp == '\t')) -- 2.47.2