@@ -673,18 +673,19 @@ static unsigned long load_elf_interp(struct elfhdr *interp_elf_ex,
last_bss = k;
bss_prot = elf_prot;
}
+
+ /*
+ * Now fill out any zeroed region (e.g. .bss): first pad the
+ * last page from the file up to the page boundary, and zero
+ * it from elf_bss up to the end of the page.
+ */
+ if (last_bss > elf_bss && padzero(elf_bss)) {
+ error = -EFAULT;
+ goto out;
+ }
}
}
- /*
- * Now fill out the bss section: first pad the last page from
- * the file up to the page boundary, and zero it from elf_bss
- * up to the end of the page.
- */
- if (padzero(elf_bss)) {
- error = -EFAULT;
- goto out;
- }
/*
* Next, align both the file and mem bss up to the page size,
* since this is where elf_bss was just zeroed up to, and where
Traditionally, only the final PT_LOAD for load_elf_interp() supported having p_memsz > p_filesz. Recently, lld's construction of musl's libc.so on PowerPC64 started having two PT_LOAD program headers with p_memsz > p_filesz. As the least invasive change possible, check for p_memsz > p_filesz for each PT_LOAD in load_elf_interp. Reported-by: Rich Felker <dalias@libc.org> Link: https://maskray.me/blog/2022-11-05-lld-musl-powerpc64 Cc: Pedro Falcato <pedro.falcato@gmail.com> Cc: Fangrui Song <maskray@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Eric Biederman <ebiederm@xmission.com> Cc: linux-fsdevel@vger.kernel.org Cc: linux-mm@kvack.org Signed-off-by: Kees Cook <keescook@chromium.org> --- Rich, Pedro, and Fangrui, are you able to test this change? I haven't constructed a trivial reproducer yet (though it would be nice to have a self-contained test-case). --- fs/binfmt_elf.c | 19 ++++++++++--------- 1 file changed, 10 insertions(+), 9 deletions(-)