diff options
Diffstat (limited to 'lib/ubsan.c')
| -rw-r--r-- | lib/ubsan.c | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/lib/ubsan.c b/lib/ubsan.c index 89ca6e580b..41a5731dda 100644 --- a/lib/ubsan.c +++ b/lib/ubsan.c @@ -382,6 +382,26 @@ void __ubsan_handle_shift_out_of_bounds(struct shift_out_of_bounds_data *data, if (suppress_report(&data->location)) return; + /* This handler would be called for code shifting a one into the + * sign bit like (1 << 31), which is all too common in barebox. + * It's technically UB, but it's so prevalent that it's highly + * unlikely to be treated by a compiler as anything else than the + * standard-compliant (1U << 31). Thus check for this case here + * and ignore it selectively + */ + if (type_is_signed(lhs_type)) { + s_max lhs_int, rhs_int; + + lhs_int = get_signed_val(lhs_type, lhs); + rhs_int = get_signed_val(rhs_type, rhs); + + if (fls(lhs_int) + rhs_int == type_bit_width(lhs_type)) { + pr_debug("signed left shift of %lld by %lld ignored.\n", + (s64)lhs_int, (s64)rhs_int); + return; + } + } + ubsan_prologue(&data->location, &flags); val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs); |