| Message ID | 20190920055955.2780-1-nicolas.iooss@m4x.org (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | [v2,1/2] libselinux: ensure strlen() is not called on NULL | expand |
On 9/20/19 1:59 AM, Nicolas Iooss wrote: > When compile_regex() calls regex_prepare_data() and this function fails > in the following condition: > > *regex = regex_data_create(); > if (!(*regex)) > return -1; > > ... error_data has been zero-ed and compile_regex() calls: > > regex_format_error(&error_data, > regex_error_format_buffer, > sizeof(regex_error_format_buffer)); > > This leads to a call to strlen(error_data->error_buffer), where > error_data->error_buffer is NULL. > > Avoid this by checking that error_data->error_buffer is not NULL before > trying to format it. > > This issue has been found using clang's static analyzer: > https://337-118970575-gh.circle-artifacts.com/0/output-scan-build/2019-09-01-181851-6152-1/report-0b122b.html#EndPath > > Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org> Personally, I would have just used a single error message for both cases (and only wrapped the condition itself with #ifdef...#else...#endif), but I'm ok with this as well. Acked-by: Stephen Smalley <sds@tycho.nsa.gov> > --- > libselinux/src/regex.c | 23 +++++++++++++++++++++++ > 1 file changed, 23 insertions(+) > > diff --git a/libselinux/src/regex.c b/libselinux/src/regex.c > index a6fcbbfec1f3..c835dd1b0e5d 100644 > --- a/libselinux/src/regex.c > +++ b/libselinux/src/regex.c > @@ -519,6 +519,29 @@ void regex_format_error(struct regex_error_data const *error_data, char *buffer, > if (pos >= buf_size) > goto truncated; > > + /* Return early if there is no error to format */ > +#ifdef USE_PCRE2 > + if (!error_data->error_code) { > + rc = snprintf(buffer + pos, buf_size - pos, "no error code"); > + if (rc < 0) > + abort(); > + pos += rc; > + if (pos >= buf_size) > + goto truncated; > + return; > + } > +#else > + if (!error_data->error_buffer) { > + rc = snprintf(buffer + pos, buf_size - pos, "empty error"); > + if (rc < 0) > + abort(); > + pos += rc; > + if (pos >= buf_size) > + goto truncated; > + return; > + } > +#endif > + > if (error_data->error_offset > 0) { > #ifdef USE_PCRE2 > rc = snprintf(buffer + pos, buf_size - pos, "At offset %zu: ", >
diff --git a/libselinux/src/regex.c b/libselinux/src/regex.c index a6fcbbfec1f3..c835dd1b0e5d 100644 --- a/libselinux/src/regex.c +++ b/libselinux/src/regex.c @@ -519,6 +519,29 @@ void regex_format_error(struct regex_error_data const *error_data, char *buffer, if (pos >= buf_size) goto truncated; + /* Return early if there is no error to format */ +#ifdef USE_PCRE2 + if (!error_data->error_code) { + rc = snprintf(buffer + pos, buf_size - pos, "no error code"); + if (rc < 0) + abort(); + pos += rc; + if (pos >= buf_size) + goto truncated; + return; + } +#else + if (!error_data->error_buffer) { + rc = snprintf(buffer + pos, buf_size - pos, "empty error"); + if (rc < 0) + abort(); + pos += rc; + if (pos >= buf_size) + goto truncated; + return; + } +#endif + if (error_data->error_offset > 0) { #ifdef USE_PCRE2 rc = snprintf(buffer + pos, buf_size - pos, "At offset %zu: ",
When compile_regex() calls regex_prepare_data() and this function fails in the following condition: *regex = regex_data_create(); if (!(*regex)) return -1; ... error_data has been zero-ed and compile_regex() calls: regex_format_error(&error_data, regex_error_format_buffer, sizeof(regex_error_format_buffer)); This leads to a call to strlen(error_data->error_buffer), where error_data->error_buffer is NULL. Avoid this by checking that error_data->error_buffer is not NULL before trying to format it. This issue has been found using clang's static analyzer: https://337-118970575-gh.circle-artifacts.com/0/output-scan-build/2019-09-01-181851-6152-1/report-0b122b.html#EndPath Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org> --- libselinux/src/regex.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+)