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08:22:05PM +0100, Matthew Wilcox wrote: > On Fri, Jul 25, 2025 at 06:10:51PM +0100, Matthew Wilcox wrote: > > On Fri, Jul 25, 2025 at 06:47:01PM +0200, Vlastimil Babka wrote: > > > On 7/25/25 08:49, Li Qiong wrote: > > > > For debugging, object_err() prints free pointer of the object. > > > > However, if check_valid_pointer() returns false for a object, > > > > dereferncing `object + s->offset` can lead to a crash. Therefore, > > > > print the object's address in such cases. > > > > I don't know where this patch came from (was it cc'd to linux-mm? i > > don't see it) Oops, I missed this email when I was replying to the previous email. > I've spent some more time thinking about this and I now believe that > there are several calls to object_err() that can be passed a bad > pointer: > > freelist_corrupted() > check_object() > on_freelist() > alloc_consistency_checks() > free_consistency_checks() > > so I think this line of attack is inappropriate. Instead, I think we > need to make object_err() resilient against wild pointers. Specifically, > avoid doing risky things in print_trailer() if object is not within slab. Making object_err() more resilient sounds good to me. -- Cheers, Harry / Hyeonggon