[PATCH] fat: Allow time_offset to be upto 24 hours

[PATCH] fat: Allow time_offset to be upto 24 hours

[Jan Kara]

Currently we limit values of time_offset mount option to be between -12
and 12 hours. However e.g. zone GMT+12 can have a DST correction on top
which makes the total time difference 13 hours. Update the checks in
mount option parsing to allow offset of upto 24 hours to allow for
unusual cases.

Reported-by: Volker Kuhlmann <list0570@paradise.net.nz>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/fat/inode.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/fs/fat/inode.c b/fs/fat/inode.c
index 509411dd3698..aa7bc11fe8fb 100644
--- a/fs/fat/inode.c
+++ b/fs/fat/inode.c
@@ -1146,7 +1146,12 @@ static int parse_options(struct super_block *sb, char *options, int is_vfat,
 		case Opt_time_offset:
 			if (match_int(&args[0], &option))
 				return -EINVAL;
-			if (option < -12 * 60 || option > 12 * 60)
+			/*
+			 * GMT+-12 zones may have DST corrections so at least
+			 * 13 hours difference is needed. Make the limit 24
+			 * just in case someone invents something unusual.
+			 */
+			if (option < -24 * 60 || option > 24 * 60)
 				return -EINVAL;
 			opts->tz_set = 1;
 			opts->time_offset = option;
-- 
2.1.4

Re: [PATCH] fat: Allow time_offset to be upto 24 hours

[OGAWA Hirofumi]

Jan Kara <jack@suse.cz> writes:

> Currently we limit values of time_offset mount option to be between -12
> and 12 hours. However e.g. zone GMT+12 can have a DST correction on top
> which makes the total time difference 13 hours. Update the checks in
> mount option parsing to allow offset of upto 24 hours to allow for
> unusual cases.
>
> Reported-by: Volker Kuhlmann <list0570@paradise.net.nz>
> Signed-off-by: Jan Kara <jack@suse.cz>

Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>

Thanks.

> ---
>  fs/fat/inode.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/fs/fat/inode.c b/fs/fat/inode.c
> index 509411dd3698..aa7bc11fe8fb 100644
> --- a/fs/fat/inode.c
> +++ b/fs/fat/inode.c
> @@ -1146,7 +1146,12 @@ static int parse_options(struct super_block *sb, char *options, int is_vfat,
>  		case Opt_time_offset:
>  			if (match_int(&args[0], &option))
>  				return -EINVAL;
> -			if (option < -12 * 60 || option > 12 * 60)
> +			/*
> +			 * GMT+-12 zones may have DST corrections so at least
> +			 * 13 hours difference is needed. Make the limit 24
> +			 * just in case someone invents something unusual.
> +			 */
> +			if (option < -24 * 60 || option > 24 * 60)
>  				return -EINVAL;
>  			opts->tz_set = 1;
>  			opts->time_offset = option;

-- 
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>