diff options
| -rw-r--r-- | kernel/kcov.c | 14 |
1 files changed, 12 insertions, 2 deletions
diff --git a/kernel/kcov.c b/kernel/kcov.c index b3732b210593..e19c84b02452 100644 --- a/kernel/kcov.c +++ b/kernel/kcov.c @@ -204,8 +204,16 @@ void notrace __sanitizer_cov_trace_pc(void) /* The first 64-bit word is the number of subsequent PCs. */ pos = READ_ONCE(area[0]) + 1; if (likely(pos < t->kcov_size)) { - area[pos] = ip; + /* Previously we write pc before updating pos. However, some + * early interrupt code could bypass check_kcov_mode() check + * and invoke __sanitizer_cov_trace_pc(). If such interrupt is + * raised between writing pc and updating pos, the pc could be + * overitten by the recursive __sanitizer_cov_trace_pc(). + * Update pos before writing pc to avoid such interleaving. + */ WRITE_ONCE(area[0], pos); + barrier(); + area[pos] = ip; } } EXPORT_SYMBOL(__sanitizer_cov_trace_pc); @@ -236,11 +244,13 @@ static void notrace write_comp_data(u64 type, u64 arg1, u64 arg2, u64 ip) start_index = 1 + count * KCOV_WORDS_PER_CMP; end_pos = (start_index + KCOV_WORDS_PER_CMP) * sizeof(u64); if (likely(end_pos <= max_pos)) { + /* See comment in __sanitizer_cov_trace_pc(). */ + WRITE_ONCE(area[0], count + 1); + barrier(); area[start_index] = type; area[start_index + 1] = arg1; area[start_index + 2] = arg2; area[start_index + 3] = ip; - WRITE_ONCE(area[0], count + 1); } } |