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commit cb5b020a8d38f77209d0472a0fea755299a8ec78
parent 23e93c9b2cde73f9912d0d8534adbddd3dcc48f4
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date:   Thu, 14 Feb 2019 15:02:18 -0800

Revert "exec: load_script: don't blindly truncate shebang string"

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 <samuel@dionne-riel.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Diffstat:
Mfs/binfmt_script.c | 10+++-------
1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/fs/binfmt_script.c b/fs/binfmt_script.c @@ -42,14 +42,10 @@ 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'))