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TencentOS-kernel/kernel/bpf
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Tony Ambardar 9fe6283a1d bpf: Fix sysfs export of empty BTF section 
commit e23bb04b0c938588eae41b7f4712b722290ed2b8 upstream.

If BTF data is missing or removed from the ELF section it is still exported
via sysfs as a zero-length file:

  root@OpenWrt:/# ls -l /sys/kernel/btf/vmlinux
  -r--r--r--    1 root    root    0 Jul 18 02:59 /sys/kernel/btf/vmlinux

Moreover, reads from this file succeed and leak kernel data:

  root@OpenWrt:/# hexdump -C /sys/kernel/btf/vmlinux|head -10
  000000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
  *
  000cc0 00 00 00 00 00 00 00 00 00 00 00 00 80 83 b0 80 |................|
  000cd0 00 10 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
  000ce0 00 00 00 00 00 00 00 00 00 00 00 00 57 ac 6e 9d |............W.n.|
  000cf0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
  *
  002650 00 00 00 00 00 00 00 10 00 00 00 01 00 00 00 01 |................|
  002660 80 82 9a c4 80 85 97 80 81 a9 51 68 00 00 00 02 |..........Qh....|
  002670 80 25 44 dc 80 85 97 80 81 a9 50 24 81 ab c4 60 |.%D.......P$...`|

This situation was first observed with kernel 5.4.x, cross-compiled for a
MIPS target system. Fix by adding a sanity-check for export of zero-length
data sections.

Fixes: 341dfcf8d78e ("btf: expose BTF info through sysfs")
Signed-off-by: Tony Ambardar <Tony.Ambardar@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/b38db205a66238f70823039a8c531535864eaac5.1600417359.git.Tony.Ambardar@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 		2021-03-16 16:37:55 +08:00
..
Makefile Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
arraymap.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
bpf_lru_list.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
bpf_lru_list.h Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
btf.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
cgroup.c bpf: Don't return EINVAL from {get,set}sockopt when optlen > PAGE_SIZE 2021-03-16 16:30:58 +08:00
core.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
cpumap.c cpumap: Avoid warning when CONFIG_DEBUG_PER_CPU_MAPS is enabled 2021-03-16 16:27:10 +08:00
devmap.c devmap: Use bpf_map_area_alloc() for allocating hash buckets 2021-03-16 16:30:57 +08:00
disasm.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
disasm.h Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
hashtab.c bpf: Remove recursion prevention from rcu free callback 2021-03-16 16:36:54 +08:00
helpers.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
inode.c bpf: Fix a rcu warning for bpffs map pretty-print 2021-03-16 16:37:35 +08:00
local_storage.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
lpm_trie.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
map_in_map.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
map_in_map.h Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
offload.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
percpu_freelist.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
percpu_freelist.h Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
queue_stack_maps.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
reuseport_array.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
stackmap.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
syscall.c bpf: sockmap: Require attach_bpf_fd when detaching a program 2021-03-16 16:32:59 +08:00
sysfs_btf.c bpf: Fix sysfs export of empty BTF section 2021-03-16 16:37:55 +08:00
tnum.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00
verifier.c bpf: Forbid XADD on spilled pointers for unprivileged users 2021-03-16 16:27:08 +08:00
xskmap.c Init Repo base on linux 5.4.32 long term, and add base tlinux kernel interfaces. 2021-03-16 11:01:34 +08:00