ujail: elf: work around GCC bug on MIPS64

Work-around gcc bug which leads to segfault parsing ELF on MIPS64.
The codepath added in this commit gets triggered when parsing
/lib/ld-musl-mips64-sf.so.1 (a symlink to /lib/libc.so) on MIPS64
(built with gcc-8.4.0 and musl 1.1.24) in qemu-system-mips64 on the
malta/be64 target.
Include work-around outputting an error message, but preventing
segfault when building for MIPS64.

Tested-by: Roman Kuzmitskii <damex.pp@icloud.com>
[tested on edgerouter 4 and edgerouter lite]
Signed-off-by: Daniel Golle <daniel@makrotopia.org>

diff --git a/jail/elf.c b/jail/elf.c
index 7c6076afb6a7f305695163ede2a796af73f9cd5e..ede85a60f0129c69581f9fabed9ddc13d2cef3ca 100644 (file)
--- a/jail/elf.c
+++ b/jail/elf.c
@@ -235,7 +235,11 @@ int elf_load_deps(const char *path, const char *map)
        unsigned int dyn_offset, dyn_size;
        unsigned int load_offset, load_vaddr;
        unsigned int interp_offset;
+#if defined(__mips__) && (__mips == 64)
+       static int gcc_mips64_bug_work_around;
 
+       gcc_mips64_bug_work_around = 1;
+#endif
        if (elf_find_section(map, PT_LOAD, &load_offset, NULL, &load_vaddr)) {
                ERROR("failed to load the .load section from %s\n", path);
                return -1;
@@ -252,6 +256,14 @@ int elf_load_deps(const char *path, const char *map)
 
        int clazz = map[EI_CLASS];
 
+#if defined(__mips__) && (__mips == 64)
+       if (gcc_mips64_bug_work_around != 1) {
+               ERROR("compiler bug: GCC for MIPS64 should be fixed!\n");
+               return -1;
+       }
+       gcc_mips64_bug_work_around = 0;
+#endif
+
        if (clazz == ELFCLASS32)
                return elf32_scan_dynamic(map, dyn_offset, dyn_size, load_vaddr - load_offset);
        else if (clazz == ELFCLASS64)