Messages in this thread | | | Date | Tue, 9 Jan 2007 16:00:51 -0800 (PST) | From | Amit Choudhary <> | Subject | Re: [PATCH] include/linux/slab.h: new KFREE() macro. |
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--- Valdis.Kletnieks@vt.edu wrote:
> On Tue, 09 Jan 2007 11:02:35 PST, Amit Choudhary said: > > Correct. And doing kfree(x); x=NULL; is not hiding that. These issues can still be debugged by > > using the slab debugging options. One other benefit of doing this is that if someone tries to > > access the same memory again using the variable 'x', then he will get an immediate crash.
What did you understand when I wrote that "if you access the same memory again using the variable 'x"?
Using variable 'x' means using variable 'x' and not variable 'y'.
And > the > > problem can be solved immediately, without using the slab debugging options. I do not yet > > understand how doing this hides the bugs, obfuscates the code, etc. because I haven't seen an > > example yet, but only blanket statements. > > char *broken() { > char *x, *y; > x = kmalloc(100); > y = x; > kfree(x); > x = NULL; > return y; > } > > Setting x to NULL doesn't do anything to fix the *real* bug here, because > the problematic reference is held in y, not x.
Did I ever say that it fixes that kind of bug?
>So you never get a crash > because somebody dereferences x. >
Dereferencing 'x' means dereferencing 'x' and not dereferencing 'y'.
-Amit
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