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| author | Tom Tromey <tom@tromey.com> | 2018-08-17 20:19:13 -0600 |
|---|---|---|
| committer | Tom Tromey <tom@tromey.com> | 2018-10-03 15:19:06 -0600 |
| commit | 4dd1b46077b2ae7331f274f7888733de5166445c (patch) | |
| tree | d23e75ce337d75dbd09e648aab85b5a68ac80244 | |
| parent | 20562150d8a894bc91657c843ee88c508188e32e (diff) | |
| download | binutils-4dd1b46077b2ae7331f274f7888733de5166445c.zip binutils-4dd1b46077b2ae7331f274f7888733de5166445c.tar.gz binutils-4dd1b46077b2ae7331f274f7888733de5166445c.tar.bz2 | |
Avoid undefined behavior in read_signed_leb128
-fsanitize=undefined pointed out that read_signed_leb128 had an
undefined left-shift when processing the final byte of a 64-bit leb:
runtime error: left shift of 127 by 63 places cannot be represented in type 'long int'
and an undefined negation:
runtime error: negation of -9223372036854775808 cannot be represented in type 'long int'; cast to an unsigned type to negate this value to itself
Both of these problems are readily avoided by havinng
read_signed_leb128 work in an unsigned type, and then casting to the
signed type at the return.
gdb/ChangeLog
2018-10-03 Tom Tromey <tom@tromey.com>
* dwarf2read.c (read_signed_leb128): Work in ULONGEST.
| -rw-r--r-- | gdb/ChangeLog | 4 | ||||
| -rw-r--r-- | gdb/dwarf2read.c | 6 |
2 files changed, 7 insertions, 3 deletions
diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 97ee73b..9731c99 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,5 +1,9 @@ 2018-10-03 Tom Tromey <tom@tromey.com> + * dwarf2read.c (read_signed_leb128): Work in ULONGEST. + +2018-10-03 Tom Tromey <tom@tromey.com> + * c-exp.y (parse_number): Work in unsigned. Remove casts. 2018-10-03 Tom Tromey <tom@tromey.com> diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c index 4013c19..7004299 100644 --- a/gdb/dwarf2read.c +++ b/gdb/dwarf2read.c @@ -19627,7 +19627,7 @@ static LONGEST read_signed_leb128 (bfd *abfd, const gdb_byte *buf, unsigned int *bytes_read_ptr) { - LONGEST result; + ULONGEST result; int shift, num_read; unsigned char byte; @@ -19639,7 +19639,7 @@ read_signed_leb128 (bfd *abfd, const gdb_byte *buf, byte = bfd_get_8 (abfd, buf); buf++; num_read++; - result |= ((LONGEST) (byte & 127) << shift); + result |= ((ULONGEST) (byte & 127) << shift); shift += 7; if ((byte & 128) == 0) { @@ -19647,7 +19647,7 @@ read_signed_leb128 (bfd *abfd, const gdb_byte *buf, } } if ((shift < 8 * sizeof (result)) && (byte & 0x40)) - result |= -(((LONGEST) 1) << shift); + result |= -(((ULONGEST) 1) << shift); *bytes_read_ptr = num_read; return result; } |