Laurent Vivier <[email protected]> writes:
> Le 26/07/2018 à 15:29, Alex Bennée a écrit:
>> I've slightly re-organised the check to more closely match the
>> sequence that the kernel uses in do_mmap().
>>
>> Signed-off-by: Alex Bennée <[email protected]>
>> Cc: umarcor <[email protected]>
>> ---
>> linux-user/mmap.c | 14 +++++++++++---
>> 1 file changed, 11 insertions(+), 3 deletions(-)
>>
>> diff --git a/linux-user/mmap.c b/linux-user/mmap.c
>> index d0c50e4888..3ef69fa2d0 100644
>> --- a/linux-user/mmap.c
>> +++ b/linux-user/mmap.c
>> @@ -391,14 +391,22 @@ abi_long target_mmap(abi_ulong start, abi_ulong len,
>> int prot,
>> }
>> #endif
>>
>> - if (offset & ~TARGET_PAGE_MASK) {
>> + if (!len) {
>> errno = EINVAL;
>> goto fail;
>> }
>>
>> len = TARGET_PAGE_ALIGN(len);
>> - if (len == 0)
>> - goto the_end;
>> + if (!len) {
>> + errno = EINVAL;
>> + goto fail;
>> + }
>
> Why do you check twice len?
> TARGET_PAGE_ALIGN() rounds up the value, so if it was not 0, it cannot
> be now.
I was trying to follow the kernel style but I realise TARGET_PAGE_ALIGN
might be a different test compared to the kernel's PAGE_ALIGN(len) for
overflows:
if (!len)
return -EINVAL;
/*
* Does the application expect PROT_READ to imply PROT_EXEC?
*
* (the exception is when the underlying filesystem is noexec
* mounted, in which case we dont add PROT_EXEC.)
*/
if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
if (!(file && path_noexec(&file->f_path)))
prot |= PROT_EXEC;
/* force arch specific MAP_FIXED handling in get_unmapped_area */
if (flags & MAP_FIXED_NOREPLACE)
flags |= MAP_FIXED;
if (!(flags & MAP_FIXED))
addr = round_hint_to_min(addr);
/* Careful about overflows.. */
len = PAGE_ALIGN(len);
if (!len)
return -ENOMEM;
>
> Thanks,
> Laurent
--
Alex Bennée
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https://bugs.launchpad.net/bugs/1783362
Title:
qemu-user: mmap should return failure (MAP_FAILED, -1) instead of
success (NULL, 0) when len==0
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