linux/tools/bpf
Kuan-Wei Chiu f04e2ad394 bpftool: Fix undefined behavior in qsort(NULL, 0, ...)
When netfilter has no entry to display, qsort is called with
qsort(NULL, 0, ...). This results in undefined behavior, as UBSan
reports:

net.c:827:2: runtime error: null pointer passed as argument 1, which is declared to never be null

Although the C standard does not explicitly state whether calling qsort
with a NULL pointer when the size is 0 constitutes undefined behavior,
Section 7.1.4 of the C standard (Use of library functions) mentions:

"Each of the following statements applies unless explicitly stated
otherwise in the detailed descriptions that follow: If an argument to a
function has an invalid value (such as a value outside the domain of
the function, or a pointer outside the address space of the program, or
a null pointer, or a pointer to non-modifiable storage when the
corresponding parameter is not const-qualified) or a type (after
promotion) not expected by a function with variable number of
arguments, the behavior is undefined."

To avoid this, add an early return when nf_link_info is NULL to prevent
calling qsort with a NULL pointer.

Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Quentin Monnet <qmo@kernel.org>
Link: https://lore.kernel.org/bpf/20240910150207.3179306-1-visitorckw@gmail.com
2024-09-10 11:40:55 -07:00
..
bpftool bpftool: Fix undefined behavior in qsort(NULL, 0, ...) 2024-09-10 11:40:55 -07:00
resolve_btfids tools/resolve_btfids: Fix comparison of distinct pointer types warning in resolve_btfids 2024-07-22 16:35:30 +02:00
runqslower tools/runqslower: Fix LDFLAGS and add LDLIBS support 2024-07-29 15:05:05 -07:00
.gitignore
bpf_asm.c
bpf_dbg.c
bpf_exp.l
bpf_exp.y
bpf_jit_disasm.c
Makefile