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mm, kfence: support kmem_dump_obj() for KFENCE objects

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Calling kmem_obj_info() via kmem_dump_obj() on KFENCE objects has been
producing garbage data due to the object not actually being maintained
by SLAB or SLUB.

Fix this by implementing __kfence_obj_info() that copies relevant
information to struct kmem_obj_info when the object was allocated by
KFENCE; this is called by a common kmem_obj_info(), which also calls the
slab/slub/slob specific variant now called __kmem_obj_info().

For completeness, kmem_dump_obj() now displays if the object was
allocated by KFENCE.

Link: https://lore.kernel.org/all/20220323090520.GG16885@xsang-OptiPlex-9020/
Link: https://lkml.kernel.org/r/20220406131558.3558585-1-elver@google.com
Fixes: b89fb5ef0c ("mm, kfence: insert KFENCE hooks for SLUB")
Fixes: d3fb45f370 ("mm, kfence: insert KFENCE hooks for SLAB")
Signed-off-by: Marco Elver <elver@google.com>
Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Reported-by: kernel test robot <oliver.sang@intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>	[slab]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Marco Elver
2022-04-14 19:13:40 -07:00
committed by Linus Torvalds
parent b1add418d4
commit 2dfe63e61c
9 changed files with 105 additions and 25 deletions
Download Patch File Download Diff File Expand all files Collapse all files

24
include/linux/kfence.h
View File

@@ -204,6 +204,22 @@ static __always_inline __must_check bool kfence_free(void *addr)
*/
bool __must_check kfence_handle_page_fault(unsigned long addr, bool is_write, struct pt_regs *regs);
#ifdef CONFIG_PRINTK
struct kmem_obj_info;
/**
* __kfence_obj_info() - fill kmem_obj_info struct
* @kpp: kmem_obj_info to be filled
* @object: the object
*
* Return:
* * false - not a KFENCE object
* * true - a KFENCE object, filled @kpp
*
* Copies information to @kpp for KFENCE objects.
*/
bool __kfence_obj_info(struct kmem_obj_info *kpp, void *object, struct slab *slab);
#endif
#else /* CONFIG_KFENCE */
static inline bool is_kfence_address(const void *addr) { return false; }
@@ -221,6 +237,14 @@ static inline bool __must_check kfence_handle_page_fault(unsigned long addr, boo
return false;
}
#ifdef CONFIG_PRINTK
struct kmem_obj_info;
static inline bool __kfence_obj_info(struct kmem_obj_info *kpp, void *object, struct slab *slab)
{
return false;
}
#endif
#endif
#endif /* _LINUX_KFENCE_H */