* [PATCH] proc: fix /proc/*/map_files lookup some more
@ 2018-02-21 18:44 Alexey Dobriyan
2018-02-21 18:51 ` Al Viro
0 siblings, 1 reply; 6+ messages in thread
From: Alexey Dobriyan @ 2018-02-21 18:44 UTC (permalink / raw)
To: akpm; +Cc: linux-kernel, avagin
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
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
---
fs/proc/base.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1913,9 +1913,11 @@ static int dname_to_vma_addr(struct dentry *dentry,
unsigned long *start, unsigned long *end)
{
const char *str = dentry->d_name.name;
+ unsigned int len = dentry->d_name.len;
unsigned long long sval, eval;
- unsigned int len;
+ if (len > 1 && *str == '0')
+ return -EINVAL;
len = _parse_integer(str, 16, &sval);
if (len & KSTRTOX_OVERFLOW)
return -EINVAL;
@@ -1927,6 +1929,9 @@ static int dname_to_vma_addr(struct dentry *dentry,
return -EINVAL;
str++;
+ len = strlen(str);
+ if (len > 1 && *str == '0')
+ return -EINVAL;
len = _parse_integer(str, 16, &eval);
if (len & KSTRTOX_OVERFLOW)
return -EINVAL;
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH] proc: fix /proc/*/map_files lookup some more
2018-02-21 18:44 [PATCH] proc: fix /proc/*/map_files lookup some more Alexey Dobriyan
@ 2018-02-21 18:51 ` Al Viro
2018-02-21 19:53 ` [PATCH v2] " Alexey Dobriyan
0 siblings, 1 reply; 6+ messages in thread
From: Al Viro @ 2018-02-21 18:51 UTC (permalink / raw)
To: Alexey Dobriyan; +Cc: akpm, linux-kernel, avagin
On Wed, Feb 21, 2018 at 09:44:11PM +0300, Alexey Dobriyan wrote:
> + len = strlen(str);
> + if (len > 1 && *str == '0')
> + return -EINVAL;
if (s[0] == '0' && s[1])
please...
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH v2] proc: fix /proc/*/map_files lookup some more
2018-02-21 18:51 ` Al Viro
@ 2018-02-21 19:53 ` Alexey Dobriyan
2018-02-21 20:04 ` Andrew Morton
0 siblings, 1 reply; 6+ messages in thread
From: Alexey Dobriyan @ 2018-02-21 19:53 UTC (permalink / raw)
To: akpm; +Cc: linux-kernel, avagin, viro
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
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
---
fs/proc/base.c | 4 ++++
1 file changed, 4 insertions(+)
--- 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;
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2] proc: fix /proc/*/map_files lookup some more
2018-02-21 19:53 ` [PATCH v2] " Alexey Dobriyan
@ 2018-02-21 20:04 ` Andrew Morton
2018-02-21 20:29 ` Cyrill Gorcunov
2018-02-21 20:58 ` Alexey Dobriyan
0 siblings, 2 replies; 6+ messages in thread
From: Andrew Morton @ 2018-02-21 20:04 UTC (permalink / raw)
To: Alexey Dobriyan; +Cc: linux-kernel, avagin, viro
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?
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2] proc: fix /proc/*/map_files lookup some more
2018-02-21 20:04 ` Andrew Morton
@ 2018-02-21 20:29 ` Cyrill Gorcunov
2018-02-21 20:58 ` Alexey Dobriyan
1 sibling, 0 replies; 6+ messages in thread
From: Cyrill Gorcunov @ 2018-02-21 20:29 UTC (permalink / raw)
To: Andrew Morton; +Cc: Alexey Dobriyan, linux-kernel, avagin, viro
On Wed, Feb 21, 2018 at 12:04:03PM -0800, Andrew Morton wrote:
>
> I don't know this code and I'm all confused.
>
> - why is the code designed to accept addresses of "0"?
It was never designed to accept addresses of 0, it is rather
a side effect of using sscanf in first place.
The address priting is done via
len = snprintf(buf, sizeof(buf), "%lx-%lx", p->start, p->end);
> - how do we know that the first digit of a VMA address will never be 0?
It should not be, due to snprintf above.
---
Thanks a lot, Alexey!
Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2] proc: fix /proc/*/map_files lookup some more
2018-02-21 20:04 ` Andrew Morton
2018-02-21 20:29 ` Cyrill Gorcunov
@ 2018-02-21 20:58 ` Alexey Dobriyan
1 sibling, 0 replies; 6+ messages in thread
From: Alexey Dobriyan @ 2018-02-21 20:58 UTC (permalink / raw)
To: Andrew Morton; +Cc: linux-kernel, avagin, viro
On Wed, Feb 21, 2018 at 12:04:03PM -0800, Andrew Morton wrote:
> 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"?
Now I'm confused.
Code rejects, say ,'07ff...-...' because printing with %lx-%lx would never
produce leading zero.
> - how do we know that the first digit of a VMA address will never be 0?
Except when address is exactly 0 but this case is handled by looking at
the second character.
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2018-02-21 21:02 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
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2018-02-21 18:44 [PATCH] proc: fix /proc/*/map_files lookup some more Alexey Dobriyan
2018-02-21 18:51 ` Al Viro
2018-02-21 19:53 ` [PATCH v2] " Alexey Dobriyan
2018-02-21 20:04 ` Andrew Morton
2018-02-21 20:29 ` Cyrill Gorcunov
2018-02-21 20:58 ` Alexey Dobriyan
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