Re: [RFC PATCH] elfload: Fix alignment when unmapping excess reservation

[Richard Henderson <richard.henderson@linaro.org>]

On 2/15/25 11:06, Richard Henderson wrote:
> On 2/13/25 06:35, Fabiano Rosas wrote:
>> When complying with the alignment requested in the ELF and unmapping
>> the excess reservation, having align_end not aligned to the guest page
>> causes the unmap to be rejected by the alignment check at
>> target_munmap and later brk adjustments hit an EEXIST.
>>
>> Fix by aligning the start of region to be unmapped.
>>
>> Fixes: c81d1fafa6 ("linux-user: Honor elf alignment when placing images")
>> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1913
>> Signed-off-by: Fabiano Rosas <farosas@suse.de>
>> ---
>> In the bug there was mention of the vdso landing in the wrong spot,
>> but I don't see evidence of this in my testing. Looking at the
>> addresses in the bug report, there seems to have been a mistake
>> because I don't see an overlap there either.
>> ---
>>   linux-user/elfload.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/linux-user/elfload.c b/linux-user/elfload.c
>> index a2c152e5ad..05ee5e74fd 100644
>> --- a/linux-user/elfload.c
>> +++ b/linux-user/elfload.c
>> @@ -3351,7 +3351,7 @@ static void load_elf_image(const char *image_name, const 
>> ImageSource *src,
>>       if (align_size != reserve_size) {
>>           abi_ulong align_addr = ROUND_UP(load_addr, align);
>> -        abi_ulong align_end = align_addr + reserve_size;
>> +        abi_ulong align_end = TARGET_PAGE_ALIGN(align_addr + reserve_size);
>>           abi_ulong load_end = load_addr + align_size;
> 
> Both align_end and load_end must be aligned.

Bah, hit ctrl-enter, not enter.  I'll fix and queue.


r~