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| author | Isaac J. Manjarres <isaacm@codeaurora.org> | 2019-08-14 01:37:37 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-08-25 11:47:44 +0300 |
| commit | 056368fc3ef7e7425a7a0c1ba3d00d4c3462db1e (patch) | |
| tree | 579dadf470bce54eb7cd1d315c43d74d0c0de03f /mm | |
| parent | c8282f1b5653b192e5066551f32a3afc6c74339b (diff) | |
| download | linux-056368fc3ef7e7425a7a0c1ba3d00d4c3462db1e.tar.xz | |
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>
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 14faadcedd06..51411f9c4068 100644 --- a/mm/usercopy.c +++ b/mm/usercopy.c @@ -151,7 +151,7 @@ static inline void check_bogus_address(const unsigned long ptr, unsigned long n, bool to_user) { /* Reject if object wraps past end of memory. */ - if (ptr + n < ptr) + if (ptr + (n - 1) < ptr) usercopy_abort("wrapped address", NULL, to_user, 0, ptr + n); /* Reject if NULL or ZERO-allocation. */ |