Commit 8099b047 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds

exec: load_script: don't blindly truncate shebang string

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: default avatarOleg Nesterov <>
Acked-by: default avatarKees Cook <>
Acked-by: default avatarMichal Hocko <>
Cc: Ben Woodard <>
Cc: "Eric W. Biederman" <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent fb5bf317
......@@ -42,10 +42,14 @@ static int load_script(struct linux_binprm *bprm)
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'))
*cp = '\0';
while (cp > bprm->buf) {
if ((*cp == ' ') || (*cp == '\t'))
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