| Message ID | 20220524152718.331773-1-alexandr.lobakin@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | modpost: fix removing numeric suffixes | expand |
On Wed, May 25, 2022 at 12:28 AM Alexander Lobakin <alexandr.lobakin@intel.com> wrote: > > With the `-z unique-symbol` linker flag or any similar mechanism, > it is possible to trigger the following: > > ERROR: modpost: "param_set_uint.0" [vmlinux] is a static EXPORT_SYMBOL > > The reason is that for now the condition from remove_dot(): > > if (m && (s[n + m] == '.' || s[n + m] == 0)) > > which was designed to test if it's a dot or a '\0' after the suffix > is never satisfied. > This is due to that `s[n + m]` always points to the last digit of a > numeric suffix, not on the symbol next to it (from a custom debug > print added to modpost): > > param_set_uint.0, s[n + m] is '0', s[n + m + 1] is '\0' > > So it's off-by-one and was like that since 2014. > > Fix this for the sake of any potential upcoming features, but don't > bother stable-backporting, as it's well hidden -- apart from that > LD flag, it can be triggered only with GCC LTO which never landed > upstream. > > Fixes: fcd38ed0ff26 ("scripts: modpost: fix compilation warning") > Signed-off-by: Alexander Lobakin <alexandr.lobakin@intel.com> > --- Applied to linux-kbuild. Thanks. > scripts/mod/modpost.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c > index 6f5c605ab0fb..fd04ba057490 100644 > --- a/scripts/mod/modpost.c > +++ b/scripts/mod/modpost.c > @@ -1905,7 +1905,7 @@ static char *remove_dot(char *s) > > if (n && s[n]) { > size_t m = strspn(s + n + 1, "0123456789"); > - if (m && (s[n + m] == '.' || s[n + m] == 0)) > + if (m && (s[n + m + 1] == '.' || s[n + m + 1] == 0)) > s[n] = 0; > } > return s; > -- > 2.36.1 >
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index 6f5c605ab0fb..fd04ba057490 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -1905,7 +1905,7 @@ static char *remove_dot(char *s) if (n && s[n]) { size_t m = strspn(s + n + 1, "0123456789"); - if (m && (s[n + m] == '.' || s[n + m] == 0)) + if (m && (s[n + m + 1] == '.' || s[n + m + 1] == 0)) s[n] = 0; } return s;
With the `-z unique-symbol` linker flag or any similar mechanism, it is possible to trigger the following: ERROR: modpost: "param_set_uint.0" [vmlinux] is a static EXPORT_SYMBOL The reason is that for now the condition from remove_dot(): if (m && (s[n + m] == '.' || s[n + m] == 0)) which was designed to test if it's a dot or a '\0' after the suffix is never satisfied. This is due to that `s[n + m]` always points to the last digit of a numeric suffix, not on the symbol next to it (from a custom debug print added to modpost): param_set_uint.0, s[n + m] is '0', s[n + m + 1] is '\0' So it's off-by-one and was like that since 2014. Fix this for the sake of any potential upcoming features, but don't bother stable-backporting, as it's well hidden -- apart from that LD flag, it can be triggered only with GCC LTO which never landed upstream. Fixes: fcd38ed0ff26 ("scripts: modpost: fix compilation warning") Signed-off-by: Alexander Lobakin <alexandr.lobakin@intel.com> --- scripts/mod/modpost.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)