On Thu, Sep 23, 2021 at 7:39 PM Kumar Kartikeya Dwivedi
<memxor@xxxxxxxxx> wrote:
>
> When a BPF object is compiled without BTF info (without -g),
> trying to link such objects using bpftool causes a SIGSEGV due to
> btf__get_nr_types accessing obj->btf which is NULL. Fix this by
> checking for the NULL pointer, and return error.
>
> Reproducer:
> $ cat a.bpf.c
> extern int foo(void);
> int bar(void) { return foo(); }
> $ cat b.bpf.c
> int foo(void) { return 0; }
> $ clang -O2 -target bpf -c a.bpf.c
> $ clang -O2 -target bpf -c b.bpf.c
> $ bpftool gen obj out a.bpf.o b.bpf.o
> Segmentation fault (core dumped)
>
> After fix:
> $ bpftool gen obj out a.bpf.o b.bpf.o
> libbpf: failed to find BTF info for object 'a.bpf.o'
> Error: failed to link 'a.bpf.o': Unknown error -22 (-22)
>
> Fixes: a46349227cd8 (libbpf: Add linker extern resolution support for functions and global variables)
> Signed-off-by: Kumar Kartikeya Dwivedi <memxor@xxxxxxxxx>
> ---
> tools/lib/bpf/linker.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
Applied to bpf, thanks.
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