kernel/linux.git/tools/lib/bpf, branch v6.18.33

libbpf: Prevent double close and leak of btf objects

2026-05-23T11:06:52+00:00

[ Upstream commit 380044c40b1636a72fd8f188b5806be6ae564279 ] Sashiko found possible double close of btf object fd [1], which happens when strdup in load_module_btfs fails at which point the obj->btf_module_cnt is already incremented. The error path close btf fd and so does later cleanup code in bpf_object_post_load_cleanup function. Also libbpf_ensure_mem failure leaves btf object not assigned and it's leaked. Replacing the err_out label with break to make the error path less confusing as suggested by Alan. Incrementing obj->btf_module_cnt only if there's no failure and releasing btf object in error path. Fixes: 91abb4a6d79d ("libbpf: Support attachment of BPF tracing programs to kernel modules") [1] https://sashiko.dev/#/patchset/20260324081846.2334094-1-jolsa%40kernel.org Signed-off-by: Jiri Olsa Link: https://lore.kernel.org/r/20260416100034.1610852-1-jolsa@kernel.org Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin

bpf: reject negative CO-RE accessor indices in bpf_core_parse_spec()

2026-05-23T11:06:30+00:00

[ Upstream commit 1c22483a2c4bbf747787f328392ca3e68619c4dc ] CO-RE accessor strings are colon-separated indices that describe a path from a root BTF type to a target field, e.g. "0:1:2" walks through nested struct members. bpf_core_parse_spec() parses each component with sscanf("%d"), so negative values like -1 are silently accepted. The subsequent bounds checks (access_idx >= btf_vlen(t)) only guard the upper bound and always pass for negative values because C integer promotion converts the __u16 btf_vlen result to int, making the comparison (int)(-1) >= (int)(N) false for any positive N. When -1 reaches btf_member_bit_offset() it gets cast to u32 0xffffffff, producing an out-of-bounds read far past the members array. A crafted BPF program with a negative CO-RE accessor on any struct that exists in vmlinux BTF (e.g. task_struct) crashes the kernel deterministically during BPF_PROG_LOAD on any system with CONFIG_DEBUG_INFO_BTF=y (default on major distributions). The bug is reachable with CAP_BPF: BUG: unable to handle page fault for address: ffffed11818b6626 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page Oops: Oops: 0000 [#1] SMP KASAN NOPTI CPU: 0 UID: 0 PID: 85 Comm: poc Not tainted 7.0.0-rc6 #18 PREEMPT(full) RIP: 0010:bpf_core_parse_spec (tools/lib/bpf/relo_core.c:354) RAX: 00000000ffffffff Call Trace: bpf_core_calc_relo_insn (tools/lib/bpf/relo_core.c:1321) bpf_core_apply (kernel/bpf/btf.c:9507) check_core_relo (kernel/bpf/verifier.c:19475) bpf_check (kernel/bpf/verifier.c:26031) bpf_prog_load (kernel/bpf/syscall.c:3089) __sys_bpf (kernel/bpf/syscall.c:6228) CO-RE accessor indices are inherently non-negative (struct member index, array element index, or enumerator index), so reject them immediately after parsing. Fixes: ddc7c3042614 ("libbpf: implement BPF CO-RE offset relocation algorithm") Reported-by: Xiang Mei Signed-off-by: Weiming Shi Reviewed-by: Emil Tsalapatis Acked-by: Paul Chaignon Link: https://lore.kernel.org/r/20260404161221.961828-2-bestswngs@gmail.com Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin

bpftool: Fix truncated netlink dumps

2026-02-26T22:59:39+00:00

[ Upstream commit 3b39d73cc3379360a33eb583b17f21fe55e1288e ] Netlink requires that the recv buffer used during dumps is at least min(PAGE_SIZE, 8k) (see the man page). Otherwise the messages will get truncated. Make sure bpftool follows this requirement, avoid missing information on systems with large pages. Acked-by: Quentin Monnet Fixes: 7084566a236f ("tools/bpftool: Remove libbpf_internal.h usage in bpftool") Signed-off-by: Jakub Kicinski Link: https://lore.kernel.org/r/20260217194150.734701-1-kuba@kernel.org Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin

libbpf: Fix invalid write loop logic in bpf_linker__add_buf()

2026-02-26T22:59:38+00:00

[ Upstream commit 04999b99e81eaa7b6223ec1c03af3bcb4ac57aaa ] Fix bpf_linker__add_buf()'s logic of copying data from memory buffer into memfd. In the event of short write not writing entire buf_sz bytes into memfd file, we'll append bytes from the beginning of buf *again* (corrupting ELF file contents) instead of correctly appending the rest of not-yet-read buf contents. Closes: https://github.com/libbpf/libbpf/issues/945 Fixes: 6d5e5e5d7ce1 ("libbpf: Extend linker API to support in-memory ELF files") Signed-off-by: Amery Hung Signed-off-by: Andrii Nakryiko Acked-by: Jiri Olsa Link: https://lore.kernel.org/bpf/20260209230134.3530521-1-ameryhung@gmail.com Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin

libbpf: Fix OOB read in btf_dump_get_bitfield_value

2026-02-26T22:59:02+00:00

[ Upstream commit 5714ca8cba5ed736f3733663c446cbee63a10a64 ] When dumping bitfield data, btf_dump_get_bitfield_value() reads data based on the underlying type's size (t->size). However, it does not verify that the provided data buffer (data_sz) is large enough to contain these bytes. If btf_dump__dump_type_data() is called with a buffer smaller than the type's size, this leads to an out-of-bounds read. This was confirmed by AddressSanitizer in the linked issue. Fix this by ensuring we do not read past the provided data_sz limit. Fixes: a1d3cc3c5eca ("libbpf: Avoid use of __int128 in typed dump display") Reported-by: Harrison Green Suggested-by: Alan Maguire Signed-off-by: Varun R Mallya Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20260106233527.163487-1-varunrmallya@gmail.com Closes: https://github.com/libbpf/libbpf/issues/928 Signed-off-by: Sasha Levin

libbpf: Fix -Wdiscarded-qualifiers under C23

2026-02-06T15:57:45+00:00

commit d70f79fef65810faf64dbae1f3a1b5623cdb2345 upstream. glibc ≥ 2.42 (GCC 15) defaults to -std=gnu23, which promotes -Wdiscarded-qualifiers to an error. In C23, strstr() and strchr() return "const char *". Change variable types to const char * where the pointers are never modified (res, sym_sfx, next_path). Suggested-by: Florian Weimer Suggested-by: Andrii Nakryiko Signed-off-by: Mikhail Gavrilov Link: https://lore.kernel.org/r/20251206092825.1471385-1-mikhail.v.gavrilov@gmail.com Signed-off-by: Alexei Starovoitov [ shung-hsi.yu: needed to fix kernel build failure due to libbpf since glibc 2.43+ (which adds 'const' qualifier to strstr) ] Signed-off-by: Shung-Hsi Yu Signed-off-by: Greg Kroah-Hartman

libbpf: Fix parsing of multi-split BTF

2025-12-18T13:02:50+00:00

[ Upstream commit 4f596acc260e691a2e348f64230392f3472feea3 ] When creating multi-split BTF we correctly set the start string offset to be the size of the base string section plus the base BTF start string offset; the latter is needed for multi-split BTF since the offset is non-zero there. Unfortunately the BTF parsing case needed that logic and it was missed. Fixes: 4e29128a9ace ("libbpf/btf: Fix string handling to support multi-split BTF") Signed-off-by: Alan Maguire Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20251104203309.318429-2-alan.maguire@oracle.com Signed-off-by: Sasha Levin

bpf: add _impl suffix for bpf_stream_vprintk() kfunc

2025-11-05T01:50:25+00:00

Rename bpf_stream_vprintk() to bpf_stream_vprintk_impl(). This makes bpf_stream_vprintk() follow the already established "_impl" suffix-based naming convention for kfuncs with the bpf_prog_aux argument provided by the verifier implicitly. This convention will be taken advantage of with the upcoming KF_IMPLICIT_ARGS feature to preserve backwards compatibility to BPF programs. Acked-by: Andrii Nakryiko Signed-off-by: Mykyta Yatsenko Link: https://lore.kernel.org/r/20251104-implv2-v3-2-4772b9ae0e06@meta.com Signed-off-by: Alexei Starovoitov Acked-by: Ihor Solodrai

libbpf: Fix powerpc's stack register definition in bpf_tracing.h

2025-10-23T18:25:16+00:00

retsnoop's build on powerpc (ppc64le) architecture ([0]) failed due to wrong definition of PT_REGS_SP() macro. Looking at powerpc's implementation of stack unwinding in perf_callchain_user_64() clearly shows that stack pointer register is gpr[1]. Fix libbpf's definition of __PT_SP_REG for powerpc to fix all this. [0] https://kojipkgs.fedoraproject.org/work/tasks/1544/137921544/build.log Fixes: 138d6153a139 ("samples/bpf: Enable powerpc support") Signed-off-by: Andrii Nakryiko Reviewed-by: Naveen N Rao (AMD) Link: https://lore.kernel.org/r/20251020203643.989467-1-andrii@kernel.org Signed-off-by: Alexei Starovoitov

libbpf: Fix undefined behavior in {get,put}_unaligned_be32()

2025-10-06T16:16:29+00:00

These violate aliasing rules and may be miscompiled unless -fno-strict-aliasing is used. Replace them with the standard memcpy() solution. Note that compilers know how to optimize this properly. Fixes: 4a1c9e544b8d ("libbpf: remove linux/unaligned.h dependency for libbpf_sha256()") Signed-off-by: Eric Biggers Signed-off-by: Andrii Nakryiko Acked-by: Yonghong Song Link: https://lore.kernel.org/bpf/20251006012037.159295-1-ebiggers@kernel.org