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BACKPORT: vsprintf: Fix %pK with kptr_restrict == 0

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Although kptr_restrict is set to 0 and the kernel is booted with
no_hash_pointers parameter, the content of /proc/vmallocinfo is
lacking the real addresses.

  / # cat /proc/vmallocinfo
  0x(ptrval)-0x(ptrval)    8192 load_module+0xc0c/0x2c0c pages=1 vmalloc
  0x(ptrval)-0x(ptrval)   12288 start_kernel+0x4e0/0x690 pages=2 vmalloc
  0x(ptrval)-0x(ptrval)   12288 start_kernel+0x4e0/0x690 pages=2 vmalloc
  0x(ptrval)-0x(ptrval)    8192 _mpic_map_mmio.constprop.0+0x20/0x44 phys=0x80041000 ioremap
  0x(ptrval)-0x(ptrval)   12288 _mpic_map_mmio.constprop.0+0x20/0x44 phys=0x80041000 ioremap
    ...

According to the documentation for /proc/sys/kernel/, %pK is
equivalent to %p when kptr_restrict is set to 0.

Bug: 254441685
Fixes: 5ead723a20 ("lib/vsprintf: no_hash_pointers prints all addresses as unhashed")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/107476128e59bff11a309b5bf7579a1753a41aca.1645087605.git.christophe.leroy@csgroup.eu
(cherry picked from commit 8484291132)
Signed-off-by: Lee Jones <joneslee@google.com>
Change-Id: I5ac3ae8796559613cedf9a259d39b99765d7165a
This commit is contained in:
Christophe Leroy
2022-02-17 09:49:59 +01:00
committed by Lee Jones
parent 712eaeb09c
commit 83ed3e2c4a
2 changed files with 22 additions and 17 deletions
Download Patch File Download Diff File Expand all files Collapse all files

3
Documentation/admin-guide/kernel-parameters.txt
View File

@@ -3416,8 +3416,7 @@
difficult since unequal pointers can no longer be difficult since unequal pointers can no longer be
compared. However, if this command-line option is compared. However, if this command-line option is
specified, then all normal pointers will have their true specified, then all normal pointers will have their true
value printed. Pointers printed via %pK may still be value printed. This option should only be specified when
hashed. This option should only be specified when
debugging the kernel. Please do not use on production debugging the kernel. Please do not use on production
kernels. kernels.

36
lib/vsprintf.c
View File

@@ -53,6 +53,10 @@
#include <linux/string_helpers.h> #include <linux/string_helpers.h>
#include "kstrtox.h" #include "kstrtox.h"
/* Disable pointer hashing if requested */
bool no_hash_pointers __ro_after_init;
EXPORT_SYMBOL_GPL(no_hash_pointers);
static unsigned long long simple_strntoull(const char *startp, size_t max_chars, static unsigned long long simple_strntoull(const char *startp, size_t max_chars,
char **endp, unsigned int base) char **endp, unsigned int base)
{ {
@@ -849,6 +853,19 @@ static char *ptr_to_id(char *buf, char *end, const void *ptr,
return pointer_string(buf, end, (const void *)hashval, spec); return pointer_string(buf, end, (const void *)hashval, spec);
} }
static char *default_pointer(char *buf, char *end, const void *ptr,
struct printf_spec spec)
{
/*
* default is to _not_ leak addresses, so hash before printing,
* unless no_hash_pointers is specified on the command line.
*/
if (unlikely(no_hash_pointers))
return pointer_string(buf, end, ptr, spec);
return ptr_to_id(buf, end, ptr, spec);
}
int kptr_restrict __read_mostly; int kptr_restrict __read_mostly;
static noinline_for_stack static noinline_for_stack
@@ -858,7 +875,7 @@ char *restricted_pointer(char *buf, char *end, const void *ptr,
switch (kptr_restrict) { switch (kptr_restrict) {
case 0: case 0:
/* Handle as %p, hash and do _not_ leak addresses. */ /* Handle as %p, hash and do _not_ leak addresses. */
return ptr_to_id(buf, end, ptr, spec); return default_pointer(buf, end, ptr, spec);
case 1: { case 1: {
const struct cred *cred; const struct cred *cred;
@@ -2118,10 +2135,6 @@ char *fwnode_string(char *buf, char *end, struct fwnode_handle *fwnode,
return widen_string(buf, buf - buf_start, end, spec); return widen_string(buf, buf - buf_start, end, spec);
} }
/* Disable pointer hashing if requested */
bool no_hash_pointers __ro_after_init;
EXPORT_SYMBOL_GPL(no_hash_pointers);
static int __init no_hash_pointers_enable(char *str) static int __init no_hash_pointers_enable(char *str)
{ {
no_hash_pointers = true; no_hash_pointers = true;
@@ -2339,7 +2352,7 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
case 'e': case 'e':
/* %pe with a non-ERR_PTR gets treated as plain %p */ /* %pe with a non-ERR_PTR gets treated as plain %p */
if (!IS_ERR(ptr)) if (!IS_ERR(ptr))
break; return default_pointer(buf, end, ptr, spec);
return err_ptr(buf, end, ptr, spec); return err_ptr(buf, end, ptr, spec);
case 'u': case 'u':
case 'k': case 'k':
@@ -2349,16 +2362,9 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
default: default:
return error_string(buf, end, "(einval)", spec); return error_string(buf, end, "(einval)", spec);
} }
default:
return default_pointer(buf, end, ptr, spec);
} }
/*
* default is to _not_ leak addresses, so hash before printing,
* unless no_hash_pointers is specified on the command line.
*/
if (unlikely(no_hash_pointers))
return pointer_string(buf, end, ptr, spec);
else
return ptr_to_id(buf, end, ptr, spec);
} }
/* /*