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Re: [PATCH 2/2] lz4 overflow bug
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From: |
Toomas Soome |
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Subject: |
Re: [PATCH 2/2] lz4 overflow bug |
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Date: |
Thu, 16 Apr 2015 07:51:50 +0300 |
> On 16.04.2015, at 7:20, Andrei Borzenkov <address@hidden> wrote:
>
> В Wed, 15 Apr 2015 23:51:16 +0300
> Toomas Soome <address@hidden> пишет:
>
>>
>> hi!
>>
>> yep, this old bug is not fixed in grub. cpy can (theoretically?) overflow.
>
> You mean "length"? Or do you really mean pointer overflow?
>
> Anyway in both cases it seems more reasonable to check when length is
> computed, not after overflow, when it is already too late.
integer overflow. from 0xFFFFFFFF to 0x0.
>
>>
>> ---
>> grub-core/fs/zfs/zfs_lz4.c | 2 ++
>> 1 file changed, 2 insertions(+)
>>
>> diff --git a/grub-core/fs/zfs/zfs_lz4.c b/grub-core/fs/zfs/zfs_lz4.c
>> index 1212a89..ca6445d 100644
>> --- a/grub-core/fs/zfs/zfs_lz4.c
>> +++ b/grub-core/fs/zfs/zfs_lz4.c
>> @@ -185,6 +185,8 @@ LZ4_uncompress_unknownOutputSize(const char *source,
>> }
>> /* copy literals */
>> cpy = op + length;
>> + if (cpy < op)
>> + goto _output_error;
>> if ((cpy > oend - COPYLENGTH) ||
>> (ip + length > iend - COPYLENGTH)) {
>> if (cpy > oend)
>
>
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