kernel/linux.git/tools/lib/bpf/libbpf.c, branch linux-7.0.y

libbpf: Prevent double close and leak of btf objects

2026-05-23T11:09:07+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

libbpf: Delay feature gate check until object prepare time

2026-02-17T22:20:24+00:00

Commit 728ff167910e ("libbpf: Add gating for arena globals relocation feature") adds a feature gate check that loads a map and BPF program to test the running kernel supports large direct offsets for LDIMM64 instructions. This check is currently used to calculate arena symbol offsets during bpf_object__collect_relos, itself called by bpf_object_open. However, the program calling bpf_object_open may not have the permissions to load maps and programs. This is the case with the BPF selftests, where bpftool is invoked at compilation time during skeleton generation. This causes errors as the feature gate unexpectedly fails with -EPERM. Avoid this by moving all the use of the FEAT_LDIMM64_FULL_RANGE_OFF feature gate to BPF object preparation time instead. Fixes: 728ff167910e ("libbpf: Add gating for arena globals relocation feature") Signed-off-by: Emil Tsalapatis Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20260217204345.548648-3-emil@etsalapatis.com

libbpf: Add gating for arena globals relocation feature

2026-02-13T22:14:27+00:00

Add feature gating for the arena globals relocation introduced in commit c1f61171d44b. The commit depends on a previous commit in the same patchset that is absent from older kernels (12a1fe6e12db "bpf/verifier: Do not limit maximum direct offset into arena map"). Without this commit, arena globals relocation with arenas >= 512MiB fails to load and breaks libbpf's backwards compatibility. Introduce a libbpf feature to check whether the running kernel allows for full range ldimm64 offset, and only relocate arena globals if it does. Fixes: c1f61171d44b ("libbpf: Move arena globals to the end of the arena") Signed-off-by: Emil Tsalapatis Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20260210184532.255475-1-emil@etsalapatis.com Signed-off-by: Alexei Starovoitov

libbpf: add fsession support

2026-01-25T02:49:36+00:00

Add BPF_TRACE_FSESSION to libbpf. Signed-off-by: Menglong Dong Link: https://lore.kernel.org/r/20260124062008.8657-9-dongml2@chinatelecom.cn Signed-off-by: Alexei Starovoitov

btf: Refactor the code by calling str_is_empty

2026-01-14T00:21:56+00:00

Calling the str_is_empty function to clarify the code and no functional changes are introduced. Signed-off-by: Donglin Peng Signed-off-by: Andrii Nakryiko Acked-by: Eduard Zingerman Link: https://lore.kernel.org/bpf/20260109130003.3313716-12-dolinux.peng@gmail.com

libbpf: Add BPF_F_CPU and BPF_F_ALL_CPUS flags support for percpu maps

2026-01-07T04:48:32+00:00

Add libbpf support for the BPF_F_CPU flag for percpu maps by embedding the cpu info into the high 32 bits of: 1. **flags**: bpf_map_lookup_elem_flags(), bpf_map__lookup_elem(), bpf_map_update_elem() and bpf_map__update_elem() 2. **opts->elem_flags**: bpf_map_lookup_batch() and bpf_map_update_batch() And the flag can be BPF_F_ALL_CPUS, but cannot be 'BPF_F_CPU | BPF_F_ALL_CPUS'. Behavior: * If the flag is BPF_F_ALL_CPUS, the update is applied across all CPUs. * If the flag is BPF_F_CPU, it updates value only to the specified CPU. * If the flag is BPF_F_CPU, lookup value only from the specified CPU. * lookup does not support BPF_F_ALL_CPUS. Acked-by: Andrii Nakryiko Signed-off-by: Leon Hwang Link: https://lore.kernel.org/r/20260107022022.12843-7-leon.hwang@linux.dev Signed-off-by: Alexei Starovoitov

Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf after 6.19-rc1

2025-12-17T05:29:38+00:00

Cross-merge BPF and other fixes after downstream PR. Signed-off-by: Alexei Starovoitov

libbpf: Move arena globals to the end of the arena

2025-12-16T18:42:55+00:00

Arena globals are currently placed at the beginning of the arena by libbpf. This is convenient, but prevents users from reserving guard pages in the beginning of the arena to identify NULL pointer dereferences. Adjust the load logic to place the globals at the end of the arena instead. Also modify bpftool to set the arena pointer in the program's BPF skeleton to point to the globals. Users now call bpf_map__initial_value() to find the beginning of the arena mapping and use the arena pointer in the skeleton to determine which part of the mapping holds the arena globals and which part is free. Suggested-by: Andrii Nakryiko Signed-off-by: Emil Tsalapatis Signed-off-by: Andrii Nakryiko Acked-by: Eduard Zingerman Link: https://lore.kernel.org/bpf/20251216173325.98465-5-emil@etsalapatis.com

libbpf: Turn relo_core->sym_off unsigned

2025-12-16T18:42:55+00:00

The symbols' relocation offsets in BPF are stored in an int field, but cannot actually be negative. When in the next patch libbpf relocates globals to the end of the arena, it is also possible to have valid offsets > 2GiB that are used to calculate the final relo offsets. Avoid accidentally interpreting large offsets as negative by turning the sym_off field unsigned. Signed-off-by: Emil Tsalapatis Signed-off-by: Andrii Nakryiko Acked-by: Eduard Zingerman Link: https://lore.kernel.org/bpf/20251216173325.98465-4-emil@etsalapatis.com

libbpf: Fix -Wdiscarded-qualifiers under C23

2025-12-10T07:23:21+00:00

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