[File] [SECURITY] Integer Overflow in ascmagic.c UTF-8 Buffer Allocation (file-5.17, 32-bit)

[Christos Zoulas]

Added the check, thanks. 

christos

> On Apr 1, 2026, at 11:19 AM, Kerwin <kerwinxia66001 at gmail.com> wrote:
> 
> Hi maintainers,
> 
> I am reporting an integer overflow vulnerability in libmagic (file-5.17) where the calculation `mlen = ulen * 6` in `file_ascmagic_with_encoding()` (ascmagic.c:141-142) overflows on 32-bit platforms, causing an undersized `malloc`. The heap corruption is mitigated by bounds checking in `encode_utf8()`, but the overflow results in a logic error / denial of service.
> 
> Please find the detailed vulnerability report and proof-of-concept files attached.
> 
> Best regards
> 
> <POC.tar>-- 
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