Messages in this thread | | | Date | Wed, 21 Feb 2018 12:04:03 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH v2] proc: fix /proc/*/map_files lookup some more |
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On Wed, 21 Feb 2018 22:53:40 +0300 Alexey Dobriyan <adobriyan@gmail.com> wrote:
> I totally forgot that _parse_integer() accepts arbitrary amount of > leading zeroes leading to the following: > > OK > # readlink /proc/1/map_files/56427ecba000-56427eddc000 > /lib/systemd/systemd > > bogus > # readlink /proc/1/map_files/00000000000056427ecba000-56427eddc000 > /lib/systemd/systemd > # readlink /proc/1/map_files/56427ecba000-00000000000056427eddc000 > /lib/systemd/systemd > > ... > > --- a/fs/proc/base.c > +++ b/fs/proc/base.c > @@ -1916,6 +1916,8 @@ static int dname_to_vma_addr(struct dentry *dentry, > unsigned long long sval, eval; > unsigned int len; > > + if (str[0] == '0' && str[1]) > + return -EINVAL; > len = _parse_integer(str, 16, &sval); > if (len & KSTRTOX_OVERFLOW) > return -EINVAL; > @@ -1927,6 +1929,8 @@ static int dname_to_vma_addr(struct dentry *dentry, > return -EINVAL; > str++; > > + if (str[0] == '0' && str[1]) > + return -EINVAL; > len = _parse_integer(str, 16, &eval); > if (len & KSTRTOX_OVERFLOW) > return -EINVAL;
I don't know this code and I'm all confused.
- why is the code designed to accept addresses of "0"?
- how do we know that the first digit of a VMA address will never be 0?
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