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authorIsaac J. Manjarres <isaacm@codeaurora.org>2019-08-14 01:37:37 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-08-25 11:47:44 +0300
commit056368fc3ef7e7425a7a0c1ba3d00d4c3462db1e (patch)
tree579dadf470bce54eb7cd1d315c43d74d0c0de03f /mm
parentc8282f1b5653b192e5066551f32a3afc6c74339b (diff)
downloadlinux-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.c2
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. */