diff options
| author | Elliot Berman <quic_eberman@quicinc.com> | 2021-08-11 18:59:14 +0300 |
|---|---|---|
| committer | Kees Cook <keescook@chromium.org> | 2021-08-11 23:11:12 +0300 |
| commit | 14c4c8e41511aa8fba7fb239b20b6539b5bce201 (patch) | |
| tree | 44d64cc2aaaaa805627fee8d6433a7efff58f6c4 /kernel/cfi.c | |
| parent | 36a21d51725af2ce0700c6ebcb6b9594aac658a6 (diff) | |
| download | linux-14c4c8e41511aa8fba7fb239b20b6539b5bce201.tar.xz | |
cfi: Use rcu_read_{un}lock_sched_notrace
If rcu_read_lock_sched tracing is enabled, the tracing subsystem can
perform a jump which needs to be checked by CFI. For example, stm_ftrace
source is enabled as a module and hooks into enabled ftrace events. This
can cause an recursive loop where find_shadow_check_fn ->
rcu_read_lock_sched -> (call to stm_ftrace generates cfi slowpath) ->
find_shadow_check_fn -> rcu_read_lock_sched -> ...
To avoid the recursion, either the ftrace codes needs to be marked with
__no_cfi or CFI should not trace. Use the "_notrace" in CFI to avoid
tracing so that CFI can guard ftrace.
Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Cc: stable@vger.kernel.org
Fixes: cf68fffb66d6 ("add support for Clang CFI")
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210811155914.19550-1-quic_eberman@quicinc.com
Diffstat (limited to 'kernel/cfi.c')
| -rw-r--r-- | kernel/cfi.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/kernel/cfi.c b/kernel/cfi.c index e17a56639766..9594cfd1cf2c 100644 --- a/kernel/cfi.c +++ b/kernel/cfi.c @@ -248,9 +248,9 @@ static inline cfi_check_fn find_shadow_check_fn(unsigned long ptr) { cfi_check_fn fn; - rcu_read_lock_sched(); + rcu_read_lock_sched_notrace(); fn = ptr_to_check_fn(rcu_dereference_sched(cfi_shadow), ptr); - rcu_read_unlock_sched(); + rcu_read_unlock_sched_notrace(); return fn; } @@ -269,11 +269,11 @@ static inline cfi_check_fn find_module_check_fn(unsigned long ptr) cfi_check_fn fn = NULL; struct module *mod; - rcu_read_lock_sched(); + rcu_read_lock_sched_notrace(); mod = __module_address(ptr); if (mod) fn = mod->cfi_check; - rcu_read_unlock_sched(); + rcu_read_unlock_sched_notrace(); return fn; } |