kernel.git/tools/lib/bpf/libbpf.c, branch linux-6.0.y

libbpf: Fix null-pointer dereference in find_prog_by_sec_insn()

2022-12-31T12:25:49Z

[ Upstream commit d0d382f95a9270dcf803539d6781d6bd67e3f5b2 ] When there are no program sections, obj->programs is left unallocated, and find_prog_by_sec_insn()'s search lands on &obj->programs[0] == NULL, and will cause null-pointer dereference in the following access to prog->sec_idx. Guard the search with obj->nr_programs similar to what's being done in __bpf_program__iter() to prevent null-pointer access from happening. Fixes: db2b8b06423c ("libbpf: Support CO-RE relocations for multi-prog sections") Signed-off-by: Shung-Hsi Yu Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20221012022353.7350-4-shung-hsi.yu@suse.com Signed-off-by: Sasha Levin

libbpf: Deal with section with no data gracefully

2022-12-31T12:25:49Z

[ Upstream commit 35a855509e6ee3442477c8ebc6827b5b5d32a7b5 ] ELF section data pointer returned by libelf may be NULL (if section has SHT_NOBITS), so null check section data pointer before attempting to copy license and kversion section. Fixes: cb1e5e961991 ("bpf tools: Collect version and license from ELF sections") Signed-off-by: Shung-Hsi Yu Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20221012022353.7350-3-shung-hsi.yu@suse.com Signed-off-by: Sasha Levin

libbpf: Use elf_getshdrnum() instead of e_shnum

2022-12-31T12:25:49Z

[ Upstream commit 51deedc9b8680953437dfe359e5268120de10e30 ] This commit replace e_shnum with the elf_getshdrnum() helper to fix two oss-fuzz-reported heap-buffer overflow in __bpf_object__open. Both reports are incorrectly marked as fixed and while still being reproducible in the latest libbpf. # clusterfuzz-testcase-minimized-bpf-object-fuzzer-5747922482888704 libbpf: loading object 'fuzz-object' from buffer libbpf: sec_cnt is 0 libbpf: elf: section(1) .data, size 0, link 538976288, flags 2020202020202020, type=2 libbpf: elf: section(2) .data, size 32, link 538976288, flags 202020202020ff20, type=1 ================================================================= ==13==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x6020000000c0 at pc 0x0000005a7b46 bp 0x7ffd12214af0 sp 0x7ffd12214ae8 WRITE of size 4 at 0x6020000000c0 thread T0 SCARINESS: 46 (4-byte-write-heap-buffer-overflow-far-from-bounds) #0 0x5a7b45 in bpf_object__elf_collect /src/libbpf/src/libbpf.c:3414:24 #1 0x5733c0 in bpf_object_open /src/libbpf/src/libbpf.c:7223:16 #2 0x5739fd in bpf_object__open_mem /src/libbpf/src/libbpf.c:7263:20 ... The issue lie in libbpf's direct use of e_shnum field in ELF header as the section header count. Where as libelf implemented an extra logic that, when e_shnum == 0 && e_shoff != 0, will use sh_size member of the initial section header as the real section header count (part of ELF spec to accommodate situation where section header counter is larger than SHN_LORESERVE). The above inconsistency lead to libbpf writing into a zero-entry calloc area. So intead of using e_shnum directly, use the elf_getshdrnum() helper provided by libelf to retrieve the section header counter into sec_cnt. Fixes: 0d6988e16a12 ("libbpf: Fix section counting logic") Fixes: 25bbbd7a444b ("libbpf: Remove assumptions about uniqueness of .rodata/.data/.bss maps") Signed-off-by: Shung-Hsi Yu Signed-off-by: Andrii Nakryiko Link: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=40868 Link: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=40957 Link: https://lore.kernel.org/bpf/20221012022353.7350-2-shung-hsi.yu@suse.com Signed-off-by: Sasha Levin

libbpf: Reject legacy 'maps' ELF section

2022-12-31T12:25:49Z

[ Upstream commit e19db6762c18ab1ddf7a3ef4d0023780c24dc1e8 ] Add explicit error message if BPF object file is still using legacy BPF map definitions in SEC("maps"). Before this change, if BPF object file is still using legacy map definition user will see a bit confusing: libbpf: elf: skipping unrecognized data section(4) maps libbpf: prog 'handler': bad map relo against 'server_map' in section 'maps' Now libbpf will be explicit about rejecting "maps" ELF section: libbpf: elf: legacy map definitions in 'maps' section are not supported by libbpf v1.0+ Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20220803214202.23750-1-andrii@kernel.org Stable-dep-of: 51deedc9b868 ("libbpf: Use elf_getshdrnum() instead of e_shnum") Signed-off-by: Sasha Levin

libbpf: Use correct return pointer in attach_raw_tp

2022-12-08T10:30:14Z

[ Upstream commit 5fd2a60aecf3a42b14fa371c55b3dbb18b229230 ] We need to pass '*link' to final libbpf_get_error, because that one holds the return value, not 'link'. Fixes: 4fa5bcfe07f7 ("libbpf: Allow BPF program auto-attach handlers to bail out") Signed-off-by: Jiri Olsa Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20221114145257.882322-1-jolsa@kernel.org Signed-off-by: Sasha Levin

libbpf: Do not require executable permission for shared libraries

2022-10-21T10:39:05Z

[ Upstream commit 9e32084ef1c33a87a736d6ce3fcb95b60dac9aa1 ] Currently, resolve_full_path() requires executable permission for both programs and shared libraries. This causes failures on distos like Debian since the shared libraries are not installed executable and Linux is not requiring shared libraries to have executable permissions. Let's remove executable permission check for shared libraries. Reported-by: Goro Fuji Signed-off-by: Hengqi Chen Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20220806102021.3867130-1-hengqi.chen@gmail.com Signed-off-by: Sasha Levin

libbpf: Fix crash if SEC("freplace") programs don't have attach_prog_fd set

2022-10-21T10:38:11Z

[ Upstream commit 749c202cb6ea40f4d7ac95c4a1217a7b506f43a8 ] Fix SIGSEGV caused by libbpf trying to find attach type in vmlinux BTF for freplace programs. It's wrong to search in vmlinux BTF and libbpf doesn't even mark vmlinux BTF as required for freplace programs. So trying to search anything in obj->vmlinux_btf might cause NULL dereference if nothing else in BPF object requires vmlinux BTF. Instead, error out if freplace (EXT) program doesn't specify attach_prog_fd during at the load time. Fixes: 91abb4a6d79d ("libbpf: Support attachment of BPF tracing programs to kernel modules") Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20220909193053.577111-3-andrii@kernel.org Signed-off-by: Sasha Levin

libbpf: Support PPC in arch_specific_syscall_pfx

2022-07-28T23:11:18Z

Commit 708ac5bea0ce ("libbpf: add ksyscall/kretsyscall sections support for syscall kprobes") added the arch_specific_syscall_pfx() function, which returns a string representing the architecture in use. As it turns out this function is currently not aware of Power PC, where NULL is returned. That's being flagged by the libbpf CI system, which builds for ppc64le and the compiler sees a NULL pointer being passed in to a %s format string. With this change we add representations for two more architectures, for Power PC and Power PC 64, and also adjust the string format logic to handle NULL pointers gracefully, in an attempt to prevent similar issues with other architectures in the future. Fixes: 708ac5bea0ce ("libbpf: add ksyscall/kretsyscall sections support for syscall kprobes") Signed-off-by: Daniel Müller Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20220728222345.3125975-1-deso@posteo.net

libbpf: make RINGBUF map size adjustments more eagerly

2022-07-19T17:01:20Z

Make libbpf adjust RINGBUF map size (rounding it up to closest power-of-2 of page_size) more eagerly: during open phase when initializing the map and on explicit calls to bpf_map__set_max_entries(). Such approach allows user to check actual size of BPF ringbuf even before it's created in the kernel, but also it prevents various edge case scenarios where BPF ringbuf size can get out of sync with what it would be in kernel. One of them (reported in [0]) is during an attempt to pin/reuse BPF ringbuf. Move adjust_ringbuf_sz() helper closer to its first actual use. The implementation of the helper is unchanged. Also make detection of whether bpf_object is already loaded more robust by checking obj->loaded explicitly, given that map->fd can be < 0 even if bpf_object is already loaded due to ability to disable map creation with bpf_map__set_autocreate(map, false). [0] Closes: https://github.com/libbpf/libbpf/pull/530 Fixes: 0087a681fa8c ("libbpf: Automatically fix up BPF_MAP_TYPE_RINGBUF size, if necessary") Signed-off-by: Andrii Nakryiko Acked-by: Yonghong Song Link: https://lore.kernel.org/r/20220715230952.2219271-1-andrii@kernel.org Signed-off-by: Alexei Starovoitov

libbpf: fallback to tracefs mount point if debugfs is not mounted

2022-07-19T16:54:28Z

Teach libbpf to fallback to tracefs mount point (/sys/kernel/tracing) if debugfs (/sys/kernel/debug/tracing) isn't mounted. Acked-by: Yonghong Song Suggested-by: Connor O'Brien Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20220715185736.898848-1-andrii@kernel.org Signed-off-by: Alexei Starovoitov