diff options
| author | Isaac J. Manjarres <isaacm@codeaurora.org> | 2019-08-13 15:37:37 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-08-25 10:51:40 +0200 |
| commit | faf6760c93af392f2ef115367d5711dab068f50f (patch) | |
| tree | 019a6fa28a76c8d61bc7561c65eacd0af5a9c103 /mm | |
| parent | 694457ee8cb1b327bbb9ab8157cea220fd866227 (diff) | |
mm/usercopy: use memory range to be accessed for wraparound check
commit 951531691c4bcaa59f56a316e018bc2ff1ddf855 upstream.
Currently, when checking to see if accessing n bytes starting at address
"ptr" will cause a wraparound in the memory addresses, the check in
check_bogus_address() adds an extra byte, which is incorrect, as the
range of addresses that will be accessed is [ptr, ptr + (n - 1)].
This can lead to incorrectly detecting a wraparound in the memory
address, when trying to read 4 KB from memory that is mapped to the the
last possible page in the virtual address space, when in fact, accessing
that range of memory would not cause a wraparound to occur.
Use the memory range that will actually be accessed when considering if
accessing a certain amount of bytes will cause the memory address to
wrap around.
Link: http://lkml.kernel.org/r/1564509253-23287-1-git-send-email-isaacm@codeaurora.org
Fixes: f5509cc18daa ("mm: Hardened usercopy")
Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org>
Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>
Co-developed-by: Prasad Sodagudi <psodagud@codeaurora.org>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Trilok Soni <tsoni@codeaurora.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[kees: backport to v4.9]
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/usercopy.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/usercopy.c b/mm/usercopy.c index 3c8da0af9695..7683c22551ff 100644 --- a/mm/usercopy.c +++ b/mm/usercopy.c @@ -124,7 +124,7 @@ static inline const char *check_kernel_text_object(const void *ptr, static inline const char *check_bogus_address(const void *ptr, unsigned long n) { /* Reject if object wraps past end of memory. */ - if ((unsigned long)ptr + n < (unsigned long)ptr) + if ((unsigned long)ptr + (n - 1) < (unsigned long)ptr) return "<wrapped address>"; /* Reject if NULL or ZERO-allocation. */ |