diff options
Diffstat (limited to 'sysdeps/x86_64/multiarch/strlen-vec.S')
| -rw-r--r-- | sysdeps/x86_64/multiarch/strlen-vec.S | 15 |
1 files changed, 14 insertions, 1 deletions
diff --git a/sysdeps/x86_64/multiarch/strlen-vec.S b/sysdeps/x86_64/multiarch/strlen-vec.S index 8f660bb9c7..439e486a43 100644 --- a/sysdeps/x86_64/multiarch/strlen-vec.S +++ b/sysdeps/x86_64/multiarch/strlen-vec.S @@ -65,12 +65,25 @@ ENTRY(strlen) ret L(n_nonzero): # ifdef AS_WCSLEN - shl $2, %RSI_LP +/* Check for overflow from maxlen * sizeof(wchar_t). If it would + overflow the only way this program doesn't have undefined behavior + is if there is a null terminator in valid memory so wcslen will + suffice. */ + mov %RSI_LP, %R10_LP + sar $62, %R10_LP + test %R10_LP, %R10_LP + jnz __wcslen_sse4_1 + sal $2, %RSI_LP # endif + /* Initialize long lived registers. */ add %RDI_LP, %RSI_LP +# ifdef AS_WCSLEN +/* Check for overflow again from s + maxlen * sizeof(wchar_t). */ + jbe __wcslen_sse4_1 +# endif mov %RSI_LP, %R10_LP and $-64, %R10_LP mov %RSI_LP, %R11_LP |