diff options
| author | Kees Cook <keescook@chromium.org> | 2020-06-25 23:37:01 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-06-29 19:41:39 +0300 |
| commit | 464e86b4abadfc490f426954b431e2ec6a9d7bd2 (patch) | |
| tree | 0f383cba11e1e20a74cea7c8652cfa1309d8128d /drivers/misc/lkdtm/usercopy.c | |
| parent | 4afc339ef0d259d415993d3d96f707a92489d91e (diff) | |
| download | linux-464e86b4abadfc490f426954b431e2ec6a9d7bd2.tar.xz | |
lkdtm: Avoid more compiler optimizations for bad writes
It seems at least Clang is able to throw away writes it knows are
destined for read-only memory, which makes things like the WRITE_RO test
fail, as the write gets elided. Instead, force the variable to be
volatile, and make similar changes through-out other tests in an effort
to avoid needing to repeat fixing these kinds of problems. Also includes
pr_err() calls in failure paths so that kernel logs are more clear in
the failure case.
Reported-by: Prasad Sodagudi <psodagud@codeaurora.org>
Suggested-by: Sami Tolvanen <samitolvanen@google.com>
Fixes: 9ae113ce5faf ("lkdtm: add tests for additional page permissions")
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20200625203704.317097-2-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/misc/lkdtm/usercopy.c')
| -rw-r--r-- | drivers/misc/lkdtm/usercopy.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/drivers/misc/lkdtm/usercopy.c b/drivers/misc/lkdtm/usercopy.c index e172719dd86d..b833367a45d0 100644 --- a/drivers/misc/lkdtm/usercopy.c +++ b/drivers/misc/lkdtm/usercopy.c @@ -304,19 +304,22 @@ void lkdtm_USERCOPY_KERNEL(void) return; } - pr_info("attempting good copy_to_user from kernel rodata\n"); + pr_info("attempting good copy_to_user from kernel rodata: %px\n", + test_text); if (copy_to_user((void __user *)user_addr, test_text, unconst + sizeof(test_text))) { pr_warn("copy_to_user failed unexpectedly?!\n"); goto free_user; } - pr_info("attempting bad copy_to_user from kernel text\n"); + pr_info("attempting bad copy_to_user from kernel text: %px\n", + vm_mmap); if (copy_to_user((void __user *)user_addr, vm_mmap, unconst + PAGE_SIZE)) { pr_warn("copy_to_user failed, but lacked Oops\n"); goto free_user; } + pr_err("FAIL: survived bad copy_to_user()\n"); free_user: vm_munmap(user_addr, PAGE_SIZE); |