Mailing List Archive: [PATCH] mm/mincore: Return EFAULT when passed an invalid address.

[PATCH] mm/mincore: Return EFAULT when passed an invalid address.

Feb 23, 2007, 3:11 PM

Post #1 of 3 (288 views)

The locking fix to sys_mincore in commit
2f77d107050abc14bc393b34bdb7b91cf670c250 returns -ENOMEM when given a
bad userspace address. It should return -EFAULT.

Signed-off-by: Joel Becker <joel.becker@oracle.com>

diff --git a/mm/mincore.c b/mm/mincore.c
index 8aca6f7..4af963c 100644
--- a/mm/mincore.c
+++ b/mm/mincore.c
@@ -122,7 +122,7 @@ asmlinkage long sys_mincore(unsigned long start, size_t len,

/* ..and we need to be passed a valid user-space range */
if (!access_ok(VERIFY_READ, (void __user *) start, len))
- return -ENOMEM;
+ return -EFAULT;

/* This also avoids any overflows on PAGE_CACHE_ALIGN */
pages = len >> PAGE_SHIFT;

--

"But then she looks me in the eye
And says, 'We're going to last forever,'
And man you know I can't begin to doubt it.
Cause it just feels so good and so free and so right,
I know we ain't never going to change our minds about it, Hey!
Here comes my girl."

Joel Becker
Principal Software Developer
Oracle
E-mail: joel.becker@oracle.com
Phone: (650) 506-8127
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Re: [PATCH] mm/mincore: Return EFAULT when passed an invalid address. [ In reply to ]

hugh at veritas

Feb 23, 2007, 5:05 PM

Post #2 of 3 (260 views)

Permalink

On Fri, 23 Feb 2007, Joel Becker wrote:

> The locking fix to sys_mincore in commit
> 2f77d107050abc14bc393b34bdb7b91cf670c250 returns -ENOMEM when given a
> bad userspace address. It should return -EFAULT.

No, I think you're getting confused by the way Linus uses access_ok
on the address range given with the access_ok on the vector address.

Before and after, an access_ok failure on the output vector address
gives -EFAULT. Before and after, an invalid address in the range
to be inspected gives -ENOMEM.

Which is consistent with the other m* system calls: -EFAULT if
arguments are inaccessible, -ENOMEM if address range is invalid.

Hugh
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Re: [PATCH] mm/mincore: Return EFAULT when passed an invalid address. [ In reply to ]

Joel.Becker at oracle

Feb 23, 2007, 7:13 PM

Post #3 of 3 (261 views)

Permalink

On Sat, Feb 24, 2007 at 01:05:27AM +0000, Hugh Dickins wrote:
> No, I think you're getting confused by the way Linus uses access_ok
> on the address range given with the access_ok on the vector address.

Whoops. Sorry for the noise.

Joel

--

Life's Little Instruction Book #451

"Don't be afraid to say, 'I'm sorry.'"

Joel Becker
Principal Software Developer
Oracle
E-mail: joel.becker@oracle.com
Phone: (650) 506-8127
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