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author | Linus Torvalds <torvalds@linux-foundation.org> | 2017-11-29 10:19:29 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-11-29 10:19:29 -0800 |
commit | da6af54dc0014d733ce014a196e4c84ee43cabec (patch) | |
tree | 39785a08f5eb4783caec2ac1e51d6084117b3357 /mm | |
parent | f55e1014f9e567d830eb3a7f57d879a34872af4b (diff) | |
parent | 6424f6bb432752c7eb90cbeeb1c31d6125bba39a (diff) | |
download | op-kernel-dev-da6af54dc0014d733ce014a196e4c84ee43cabec.zip op-kernel-dev-da6af54dc0014d733ce014a196e4c84ee43cabec.tar.gz |
Merge tag 'printk-hash-pointer-4.15-rc2' of git://github.com/tcharding/linux
Pull printk pointer hashing update from Tobin Harding:
"Here is the patch set that implements hashing of printk specifier %p.
First we have two clean up patches then we do the hashing. Hashing is
done via the SipHash algorithm. The next patch adds printk specifier
%px for printing pointers when we _really_ want to see the address i.e
%px is functionally equivalent to %lx. Final patch in the set fixes
KASAN since we break it by hashing %p.
For the record here is the justification for the series:
Currently there exist approximately 14 000 places in the Kernel
where addresses are being printed using an unadorned %p. This
potentially leaks sensitive information about the Kernel layout in
memory. Many of these calls are stale, instead of fixing every call
we hash the address by default before printing. We then add %px to
provide a way to print the actual address. Although this is
achievable using %lx, using %px will assist us if we ever want to
change pointer printing behaviour. %px is more uniquely grep'able
(there are already >50 000 uses of %lx).
The added advantage of hashing %p is that security is now opt-out,
if you _really_ want the address you have to work a little harder
and use %px.
This will of course break some users, forcing code printing needed
addresses to be updated"
[ I do expect this to be an annoyance, and a number of %px users to be
added for debuggability. But nobody is willing to audit existing %p
users for information leaks, and a number of places really only use
the pointer as an object identifier rather than really 'I need the
address'.
IOW - sorry for the inconvenience, but it's the least inconvenient of
the options. - Linus ]
* tag 'printk-hash-pointer-4.15-rc2' of git://github.com/tcharding/linux:
kasan: use %px to print addresses instead of %p
vsprintf: add printk specifier %px
printk: hash addresses printed with %p
vsprintf: refactor %pK code out of pointer()
docs: correct documentation for %pK
Diffstat (limited to 'mm')
-rw-r--r-- | mm/kasan/report.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/mm/kasan/report.c b/mm/kasan/report.c index 6bcfb01..410c823 100644 --- a/mm/kasan/report.c +++ b/mm/kasan/report.c @@ -134,7 +134,7 @@ static void print_error_description(struct kasan_access_info *info) pr_err("BUG: KASAN: %s in %pS\n", bug_type, (void *)info->ip); - pr_err("%s of size %zu at addr %p by task %s/%d\n", + pr_err("%s of size %zu at addr %px by task %s/%d\n", info->is_write ? "Write" : "Read", info->access_size, info->access_addr, current->comm, task_pid_nr(current)); } @@ -206,7 +206,7 @@ static void describe_object_addr(struct kmem_cache *cache, void *object, const char *rel_type; int rel_bytes; - pr_err("The buggy address belongs to the object at %p\n" + pr_err("The buggy address belongs to the object at %px\n" " which belongs to the cache %s of size %d\n", object, cache->name, cache->object_size); @@ -225,7 +225,7 @@ static void describe_object_addr(struct kmem_cache *cache, void *object, } pr_err("The buggy address is located %d bytes %s of\n" - " %d-byte region [%p, %p)\n", + " %d-byte region [%px, %px)\n", rel_bytes, rel_type, cache->object_size, (void *)object_addr, (void *)(object_addr + cache->object_size)); } @@ -302,7 +302,7 @@ static void print_shadow_for_address(const void *addr) char shadow_buf[SHADOW_BYTES_PER_ROW]; snprintf(buffer, sizeof(buffer), - (i == 0) ? ">%p: " : " %p: ", kaddr); + (i == 0) ? ">%px: " : " %px: ", kaddr); /* * We should not pass a shadow pointer to generic * function, because generic functions may try to |