In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
bpf: Fix NULL-ptr-deref in btf_var_show()<\/p>\n
btf_var_show() calls btf_type_id_resolve() unconditionally, which
\ndereferences btf->resolved_ids. That is NULL for a base BTF – e.g. the
\nvmlinux BTF that bpf_snprintf_btf() renders against – since base BTF is
\nnot resolved during parsing. btf_modifier_show() guards this with
\n‘if (btf->resolved_ids)’, but btf_var_show() does not.<\/p>\n
A BPF program that passes the type_id of a BTF_KIND_VAR from the vmlinux
\nBTF to bpf_snprintf_btf() thus NULL-derefs:<\/p>\n
KASAN: probably user-memory-access in range [0x46638-0x4663f]
\nRIP: 0010:btf_var_show (kernel\/bpf\/btf.c:2929)
\nCall Trace:<\/p>\n
btf_type_show (kernel\/bpf\/btf.c:8259)
\n btf_type_snprintf_show (kernel\/bpf\/btf.c:8329)
\n bpf_snprintf_btf (kernel\/trace\/bpf_trace.c:1047)
\n bpf_prog_test_run_raw_tp (net\/bpf\/test_run.c:829)
\n __sys_bpf (kernel\/bpf\/syscall.c:4804)
\n do_syscall_64 (arch\/x86\/entry\/syscall_64.c:84)
\n entry_SYSCALL_64_after_hwframe (arch\/x86\/entry\/entry_64.S:121)<\/p>\n
Resolve the var’s type directly with btf_type_skip_modifiers() when
\nresolved_ids is NULL, mirroring btf_modifier_show().<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
bpf: Fix NULL-ptr-deref in btf_var_show()<\/p>\n
btf_var_show() calls btf_type_id_resolve() unconditionally, which
\ndereferences btf->reso<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-29218","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/29218","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln"}],"about":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/types\/vuln"}],"wp:attachment":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=29218"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=29218"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=29218"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}