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authorElliot Berman <quic_eberman@quicinc.com>2021-08-11 18:59:14 +0300
committerKees Cook <keescook@chromium.org>2021-08-11 23:11:12 +0300
commit14c4c8e41511aa8fba7fb239b20b6539b5bce201 (patch)
tree44d64cc2aaaaa805627fee8d6433a7efff58f6c4 /kernel/cfi.c
parent36a21d51725af2ce0700c6ebcb6b9594aac658a6 (diff)
downloadlinux-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.c8
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;
}