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Fix root mounting with no mount options 

The "trivial conversion" in commit cccaa5e335 ("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 <linux@dominikbrodowski.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Reported-by: Ondřej Jirman <megi@xff.cz>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Reported-and-tested-by: Borislav Petkov <bp@suse.de>
Tested-by: Chris Clayton <chris2553@googlemail.com>
Tested-by: Eric Biggers <ebiggers@kernel.org>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Tested-by: Guido Günther <agx@sigxcpu.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Linus Torvalds 2019-12-15 19:50:23 -08:00
parent d1eef1c619
commit 7de7de7ca0
1 changed files with 13 additions and 10 deletions
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23
init/do_mounts.c
View File

@ -391,17 +391,19 @@ static int __init do_mount_root(const char *name, const char *fs,
const int flags, const void *data) const int flags, const void *data)
{ {
struct super_block *s; struct super_block *s;
char *data_page; struct page *p = NULL;
struct page *p; char *data_page = NULL;
int ret; int ret;
/* do_mount() requires a full page as fifth argument */ if (data) {
p = alloc_page(GFP_KERNEL); /* do_mount() requires a full page as fifth argument */
if (!p) p = alloc_page(GFP_KERNEL);
return -ENOMEM; if (!p)
return -ENOMEM;
data_page = page_address(p); data_page = page_address(p);
strncpy(data_page, data, PAGE_SIZE - 1); /* 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); ret = do_mount(name, "/root", fs, flags, data_page);
if (ret) if (ret)
@ -417,7 +419,8 @@ static int __init do_mount_root(const char *name, const char *fs,
MAJOR(ROOT_DEV), MINOR(ROOT_DEV)); MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
out: out:
put_page(p); if (p)
put_page(p);
return ret; return ret;
} }