| Message ID | 20240907170454.1660578-1-jesse.huang@sifive.com |
|---|---|
| State | New |
| Headers | show |
| Series | elf: Initialize tunables_env_alias with loop to avoid memset | expand |
On Sat, Sep 7, 2024 at 10:05 AM Jesse Huang <jesse.huang@sifive.com> wrote: > > In static binaries, __tunables_init is called before the IREL relocation > is performed. This causes a problem where IFUNC for memset is provided, > because the initializer list here is translated to a call to memset, > which gets redirected to the PLT. Why doesn't dl-symbol-redir-ifunc.h work for you? > At the moment, all of the GOT entries still points to the top of the PLT, > thus the call first jump to the entry of memset in PLT, then jump to the > first entry of PLT, that finally leads to a infinite loop. > > Fixed by using a for loop to initialize the array. > --- > elf/dl-tunables.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/elf/dl-tunables.c b/elf/dl-tunables.c > index 147cc4cf23..33f88ccf55 100644 > --- a/elf/dl-tunables.c > +++ b/elf/dl-tunables.c > @@ -301,7 +301,9 @@ __tunables_init (char **envp) > return; > > enum { tunable_num_env_alias = array_length (tunable_env_alias_list) }; > - struct tunable_toset_t tunables_env_alias[tunable_num_env_alias] = { 0 }; > + struct tunable_toset_t tunables_env_alias[tunable_num_env_alias]; > + for (int i = 0; i < tunable_num_env_alias; i++) > + tunables_env_alias[i] = (struct tunable_toset_t) { NULL, NULL, 0 }; > > while ((envp = get_next_env (envp, &envname, &envval, &prev_envp)) != NULL) > { > -- > 2.46.0 >
I was completely unaware of the file and it indeed solved our problem. Thank you for pointing it out! -- Jesse Huang H.J. Lu <hjl.tools@gmail.com> 於 2024年9月8日 週日 上午1:33寫道： > On Sat, Sep 7, 2024 at 10:05 AM Jesse Huang <jesse.huang@sifive.com> > wrote: > > > > In static binaries, __tunables_init is called before the IREL relocation > > is performed. This causes a problem where IFUNC for memset is provided, > > because the initializer list here is translated to a call to memset, > > which gets redirected to the PLT. > > Why doesn't dl-symbol-redir-ifunc.h work for you? > > > At the moment, all of the GOT entries still points to the top of the PLT, > > thus the call first jump to the entry of memset in PLT, then jump to the > > first entry of PLT, that finally leads to a infinite loop. > > > > Fixed by using a for loop to initialize the array. > > --- > > elf/dl-tunables.c | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/elf/dl-tunables.c b/elf/dl-tunables.c > > index 147cc4cf23..33f88ccf55 100644 > > --- a/elf/dl-tunables.c > > +++ b/elf/dl-tunables.c > > @@ -301,7 +301,9 @@ __tunables_init (char **envp) > > return; > > > > enum { tunable_num_env_alias = array_length (tunable_env_alias_list) > }; > > - struct tunable_toset_t tunables_env_alias[tunable_num_env_alias] = { > 0 }; > > + struct tunable_toset_t tunables_env_alias[tunable_num_env_alias]; > > + for (int i = 0; i < tunable_num_env_alias; i++) > > + tunables_env_alias[i] = (struct tunable_toset_t) { NULL, NULL, 0 }; > > > > while ((envp = get_next_env (envp, &envname, &envval, &prev_envp)) != > NULL) > > { > > -- > > 2.46.0 > > > > > -- > H.J. >
diff --git a/elf/dl-tunables.c b/elf/dl-tunables.c index 147cc4cf23..33f88ccf55 100644 --- a/elf/dl-tunables.c +++ b/elf/dl-tunables.c @@ -301,7 +301,9 @@ __tunables_init (char **envp) return; enum { tunable_num_env_alias = array_length (tunable_env_alias_list) }; - struct tunable_toset_t tunables_env_alias[tunable_num_env_alias] = { 0 }; + struct tunable_toset_t tunables_env_alias[tunable_num_env_alias]; + for (int i = 0; i < tunable_num_env_alias; i++) + tunables_env_alias[i] = (struct tunable_toset_t) { NULL, NULL, 0 }; while ((envp = get_next_env (envp, &envname, &envval, &prev_envp)) != NULL) {