On Thu, Jun 25, 2020 at 5:47 PM H. Nikolaus Schaller <hns@xxxxxxxxxxxxx> wrote: > > strsep() is neither standard C nor POSIX and used outside > the kernel code here. Using it here requires that the > build host supports it out of the box which is e.g. > not true for a Darwin build host and using a cross-compiler. > This leads to: > > scripts/mod/modpost.c:145:2: warning: implicit declaration of function 'strsep' [-Wimplicit-function-declaration] > return strsep(stringp, "\n"); > ^ > > and a segfault when running MODPOST. > > See also: https://stackoverflow.com/a/7219504 > > So let's add some lines of code separating the string at the > next newline character instead of using strsep(). It does not > hurt kernel size or speed since this code is run on the build host. > > Fixes: ac5100f5432967 ("modpost: add read_text_file() and get_line() helpers") > Signed-off-by: H. Nikolaus Schaller <hns@xxxxxxxxxxxxx> > --- > scripts/mod/modpost.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c > index 6aea65c65745..8fe63989c6e1 100644 > --- a/scripts/mod/modpost.c > +++ b/scripts/mod/modpost.c > @@ -138,11 +138,16 @@ char *read_text_file(const char *filename) > > char *get_line(char **stringp) > { > + char *p; > /* do not return the unwanted extra line at EOF */ > if (*stringp && **stringp == '\0') This check does not make sense anymore. Previously, get_line(NULL) returns NULL. With your patch, get_line(NULL) crashes due to NULL-pointer dereference. > return NULL; > > - return strsep(stringp, "\n"); > + p = *stringp; > + while (**stringp != '\n') > + (*stringp)++; Is this a safe conversion? If the input file does not contain '\n' at all, this while-loop continues running, and results in the segmentation fault due to buffer over-run. > + *(*stringp)++ = '\0'; > + return p; > } How about this? char *get_line(char **stringp) { char *orig = *stringp; char *next; /* do not return the unwanted extra line at EOF */ if (!orig || *orig == '\0') return NULL; next = strchr(orig, '\n'); if (next) *next++ = '\0'; *stringp = next; return orig; } > /* A list of all modules we processed */ > -- > 2.26.2 > -- Best Regards Masahiro Yamada
