Re: [PATCH] tools/mm/thpmaps: handle carriage returns and non-UTF-8 filenames

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] tools/mm/thpmaps: UnicodeEncodeError in vma_print() on non-UTF-8 filenames
--

commit 5f793a93e6fde4bbef2fd7ad6b6bda119aa8b288
Author: Weilin Tong <tongweilin@linux.alibaba.com>

tools/mm/thpmaps: handle carriage returns and non-UTF-8 filenames

This commit updates VMAList.__init__() in tools/mm/thpmaps to open
/proc/<pid>/smaps with newline='\n' and errors='surrogateescape' so that
carriage returns in mapped filenames do not split header lines and
non-UTF-8 bytes do not raise UnicodeDecodeError while reading.

Link: https://lore.kernel.org/linux-mm/20261101211644.c63a2028bbede0f763f41f80@linux-foundation.org/

> diff --git a/tools/mm/thpmaps b/tools/mm/thpmaps
> index a1a9bc30514f3..f89568bd499ec 100644
> --- a/tools/mm/thpmaps
> +++ b/tools/mm/thpmaps
> @@ -196,7 +196,8 @@ class VMAList:
>      # instance to receive VMAs.
>      def __init__(self, pid='self', stats=[]):
>          self.vmas = []
> -        with open(f'/proc/{pid}/smaps', 'r') as file:
> +        with open(f'/proc/{pid}/smaps', 'r', newline='\n',
> +                  errors='surrogateescape') as file:

[Severity: Medium]
When VMAList.__init__() opens /proc/<pid>/smaps with
errors='surrogateescape', non-UTF-8 bytes in a mapped filename are decoded
into lone surrogate code points in vma.name.

In default (non-rollup) mode, do_main() passes each VMA to vma_print():

tools/mm/thpmaps:do_main() {
    ...
                        if args.rollup:
                            ...
                        else:
                            vma_print(vma, pid)
                            stats_print(stats, vma_anon, vma_file, args.inc_empty)
        except (FileNotFoundError, ProcessLookupError, FileIOException):
    ...
}

And vma_print() writes vma.name directly to sys.stdout via print():

tools/mm/thpmaps:vma_print() {
    print("{:010d}: {:016x}-{:016x} {}{}{}{} {:08x} {:02x}:{:02x} {:08x} {}"
        .format(
            pid, vma.start, vma.end,
            'r' if vma.read else '-', 'w' if vma.write else '-',
            'x' if vma.execute else '-', 'p' if vma.private else 's',
            vma.pgoff, vma.major, vma.minor, vma.inode, vma.name
        ))
}

Under standard UTF-8 locales, sys.stdout uses errors='strict' by default,
which rejects lone surrogates. Doesn't printing a VMA with non-UTF-8
filename bytes in vma_print() still terminate the script with an uncaught
UnicodeEncodeError unless sys.stdout is also reconfigured (for example with
errors='surrogateescape' or errors='backslashreplace') or vma.name is
sanitized before printing?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261102085419.696232-1-tongweilin@linux.alibaba.com?part=1