In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
bpf: Reject sleepable BPF_LSM_CGROUP programs at load time<\/p>\n
The cgroup shim runs under rcu_read_lock_dont_migrate(), so we should
\nnot attach any sleepable BPF programs there. Add support to the verifier
\nto explicitly reject attempts to load sleepable BPF programs destined
\nfor LSM cgroup attachment.<\/p>\n
Without this, we get the following splat from a BPF_LSM_CGROUP
\nprogram marked BPF_F_SLEEPABLE attached to file_open when it calls
\nbpf_get_dentry_xattr():<\/p>\n
BUG: sleeping function called from invalid context at kernel\/locking\/rwsem.c:1567
\n in_atomic(): 0, irqs_disabled(): 0, non_block: 0, pid: 34317, name: load
\n preempt_count: 0, expected: 0
\n RCU nest depth: 2, expected: 0
\n Call Trace:
\n down_read+0x76\/0x480
\n ext4_xattr_get+0x11f\/0x700
\n __vfs_getxattr+0xf0\/0x150
\n bpf_get_dentry_xattr+0xbb\/0xf0
\n bpf_prog_e76a298dac9218c6_test_open+0x6a\/0x85
\n __cgroup_bpf_run_lsm_current+0x326\/0x840
\n bpf_trampoline_6442534646+0x62\/0x14d
\n security_file_open+0x34\/0x60
\n do_dentry_open+0x340\/0x1260
\n vfs_open+0x7a\/0x440
\n path_openat+0x1bac\/0x30a0<\/p>\n
libbpf provides a .s named section variant for every sleepable
\nprogram type except lsm_cgroup, reflecting that per-cgroup LSM programs
\nare intended to only run in a non-sleepable context.<\/p>\n
The above splat was obtained by bypassing libbpf by using bpf(2)
\ndirectly.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
bpf: Reject sleepable BPF_LSM_CGROUP programs at load time<\/p>\n
The cgroup shim runs under rcu_read_lock_dont_migrate(), so we should
\nn<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-7284","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/7284","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=7284"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=7284"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=7284"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}