From c28d5c11dc55f6f2a50194cdc14ec7ecf1222032 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 15 Dec 2019 19:50:23 -0800 Subject: [PATCH] Fix root mounting with no mount options MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit The "trivial conversion" in commit 7d4e64e1cd48 ("init: use do_mount() instead of ksys_mount()") was totally broken, since it didn't handle the case of a NULL mount data pointer. And while I had "tested" it (and presumably Dominik had too) that bug was hidden by me having options. Cc: Dominik Brodowski Cc: Arnd Bergmann Reported-by: Ondřej Jirman Reported-by: Guenter Roeck Reported-by: Naresh Kamboju Reported-and-tested-by: Borislav Petkov Tested-by: Chris Clayton Tested-by: Eric Biggers Tested-by: Geert Uytterhoeven Tested-by: Guido Günther Signed-off-by: Linus Torvalds --- init/do_mounts.c | 23 +++++++++++++---------- 1 file changed, 13 insertions(+), 10 deletions(-) diff --git a/init/do_mounts.c b/init/do_mounts.c index f55cbd9cb8183..0ae9cc22f2ae2 100644 --- a/init/do_mounts.c +++ b/init/do_mounts.c @@ -391,17 +391,19 @@ static int __init do_mount_root(const char *name, const char *fs, const int flags, const void *data) { struct super_block *s; - char *data_page; - struct page *p; + struct page *p = NULL; + char *data_page = NULL; int ret; - /* do_mount() requires a full page as fifth argument */ - p = alloc_page(GFP_KERNEL); - if (!p) - return -ENOMEM; - - data_page = page_address(p); - strncpy(data_page, data, PAGE_SIZE - 1); + if (data) { + /* do_mount() requires a full page as fifth argument */ + p = alloc_page(GFP_KERNEL); + if (!p) + return -ENOMEM; + data_page = page_address(p); + /* zero-pad. do_mount() will make sure it's terminated */ + strncpy(data_page, data, PAGE_SIZE); + } ret = do_mount(name, "/root", fs, flags, data_page); if (ret) @@ -417,7 +419,8 @@ static int __init do_mount_root(const char *name, const char *fs, MAJOR(ROOT_DEV), MINOR(ROOT_DEV)); out: - put_page(p); + if (p) + put_page(p); return ret; } -- 2.39.5