On Wed, Feb 03, 2010 at 03:13:30PM -0600, Eric Sandeen wrote:
> We have 2 mount options, "barrier" and "auto_da_alloc"
> which may or may not take a 1/0 argument. This is confusing
> the parser, it seems, because if we pass it without an
> arg, it still tries to match_int for the arg, which
> is uninitialized, and match_number uses those uninit from/to
> values to do a kmalloc, resulting in potentially noisy
> failures.
>
> I think just defining _arg variants of the tokens and
> handling them separately is the simplest fix.
>
> Reported-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
> Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
> ---
This fix works just as well, and doesn't require _arg and _no_arg
versions of the token tags.
As long as we initialize arg[0], things should work correctly. They
work correctly even without !args[0].from check, but I added that just
in case the implementation of the match_token library function changes
in the future.
- Ted
commit 1e6276ea260bcd37284f4387c435239919fbc628
Author: Theodore Ts'o <tytso@xxxxxxx>
Date: Mon Feb 15 11:00:12 2010 -0500
ext4: Fix optional-arg mount options
We have 2 mount options, "barrier" and "auto_da_alloc" which may or
may not take a 1/0 argument. This causes the ext4 superblock mount
code to subtract uninitialized pointers and pass the result to
kmalloc, which results in very noisy failures.
Reported-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Signed-off-by: "Theodore Ts'o" <tytso@xxxxxxx>
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 735c20d..7e9a7ea 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1229,6 +1229,7 @@ static int parse_options(char *options, struct super_block *sb,
if (!*p)
continue;
+ args[0].to = args[0].from = 0;
token = match_token(p, tokens, args);
switch (token) {
case Opt_bsd_df:
@@ -1518,7 +1519,7 @@ set_qf_format:
clear_opt(sbi->s_mount_opt, BARRIER);
break;
case Opt_barrier:
- if (match_int(&args[0], &option)) {
+ if (!args[0].from || match_int(&args[0], &option)) {
set_opt(sbi->s_mount_opt, BARRIER);
break;
}
@@ -1594,7 +1595,7 @@ set_qf_format:
set_opt(sbi->s_mount_opt,NO_AUTO_DA_ALLOC);
break;
case Opt_auto_da_alloc:
- if (match_int(&args[0], &option)) {
+ if (!args[0].from || match_int(&args[0], &option)) {
clear_opt(sbi->s_mount_opt, NO_AUTO_DA_ALLOC);
break;
}
--
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