From: Lukas Czerner <lczerner@redhat.com>
Date: Thu, 22 Mar 2012 01:22:22 +0000 (-0400)
Subject: ext4: fix start and len arguments handling in ext4_trim_fs()
X-Git-Tag: v3.4-rc1~75^2~9
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=913eed83eda42012cde8a9a801c31b312545c098;p=pandora-kernel.git

ext4: fix start and len arguments handling in ext4_trim_fs()

The overflow can happen when we are calling get_group_no_and_offset()
which stores the group number in the ext4_grpblk_t type which is
actually int. However when the blocknr is big enough the group number
might be bigger than ext4_grpblk_t resulting in overflow. This will
most likely happen with FITRIM default argument len = ULLONG_MAX.

Fix this by using "end" variable instead of "start+len" as it is easier
to get right and specifically check that the end is not beyond the end
of the file system, so we are sure that the result of
get_group_no_and_offset() will not overflow. Otherwise truncate it to
the size of the file system.

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
---

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