lkml.org 
[lkml]   [2020]   [Apr]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [RFC 1/1] ext4: Fix overflow case for map.m_len in ext4_iomap_begin_*
From
Date

Sorry Jan and others. Please ignore this patch.
I will resend a proper one after making sure it is tested via syzbot.

On 4/14/20 9:20 PM, Jan Kara wrote:
> On Sun 12-04-20 14:54:35, Ritesh Harjani wrote:
>> EXT4_MAX_LOGICAL_BLOCK - map.m_lblk + 1 in case when
>> map.m_lblk (offset) is 0 could overflow an unsigned int
>> and become 0.
>>
>> Fix this.
>>
>> Signed-off-by: Ritesh Harjani <riteshh@linux.ibm.com>
>> Reported-by: syzbot+77fa5bdb65cc39711820@syzkaller.appspotmail.com
>> Fixes: d3b6f23f7167 ("ext4: move ext4_fiemap to use iomap framework")
>
> The patch looks good to me. You can add:
>
> Reviewed-by: Jan Kara <jack@suse.cz>
>
> Honza
>
>> ---
>> fs/ext4/inode.c | 12 ++++++++++--
>> 1 file changed, 10 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
>> index e416096fc081..d630ec7a9c8e 100644
>> --- a/fs/ext4/inode.c
>> +++ b/fs/ext4/inode.c
>> @@ -3424,6 +3424,7 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
>> int ret;
>> struct ext4_map_blocks map;
>> u8 blkbits = inode->i_blkbits;
>> + loff_t len;
>>
>> if ((offset >> blkbits) > EXT4_MAX_LOGICAL_BLOCK)
>> return -EINVAL;
>> @@ -3435,8 +3436,11 @@ static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
>> * Calculate the first and last logical blocks respectively.
>> */
>> map.m_lblk = offset >> blkbits;
>> - map.m_len = min_t(loff_t, (offset + length - 1) >> blkbits,
>> + len = min_t(loff_t, (offset + length - 1) >> blkbits,
>> EXT4_MAX_LOGICAL_BLOCK) - map.m_lblk + 1;
>> + if (len > EXT4_MAX_LOGICAL_BLOCK)
>> + len = EXT4_MAX_LOGICAL_BLOCK;
>> + map.m_len = len;
>>
>> if (flags & IOMAP_WRITE)
>> ret = ext4_iomap_alloc(inode, &map, flags);
>> @@ -3524,6 +3528,7 @@ static int ext4_iomap_begin_report(struct inode *inode, loff_t offset,
>> bool delalloc = false;
>> struct ext4_map_blocks map;
>> u8 blkbits = inode->i_blkbits;
>> + loff_t len
>>
>> if ((offset >> blkbits) > EXT4_MAX_LOGICAL_BLOCK)
>> return -EINVAL;
>> @@ -3541,8 +3546,11 @@ static int ext4_iomap_begin_report(struct inode *inode, loff_t offset,
>> * Calculate the first and last logical block respectively.
>> */
>> map.m_lblk = offset >> blkbits;
>> - map.m_len = min_t(loff_t, (offset + length - 1) >> blkbits,
>> + len = min_t(loff_t, (offset + length - 1) >> blkbits,
>> EXT4_MAX_LOGICAL_BLOCK) - map.m_lblk + 1;
>> + if (len > EXT4_MAX_LOGICAL_BLOCK)
>> + len = EXT4_MAX_LOGICAL_BLOCK;
>> + map.m_len = len;
>>
>> /*
>> * Fiemap callers may call for offset beyond s_bitmap_maxbytes.
>> --
>> 2.21.0
>>

\
 
 \ /
  Last update: 2020-04-16 09:39    [W:0.054 / U:0.904 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site