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authorIlya Leoshkevich <iii@linux.ibm.com>2019-08-16 12:53:00 +0200
committerDaniel Borkmann <daniel@iogearbox.net>2019-09-16 11:44:05 +0200
commitd895a0f16fadb26d22ab531c49768f7642ae5c3e (patch)
treed37c4f163bc37e8bce4150c075db214d7d1af389 /include/linux/filter.h
parentaf58e7ee6a8d83726ad8a2696e98d86400a7639c (diff)
bpf: fix accessing bpf_sysctl.file_pos on s390
"ctx:file_pos sysctl:read write ok" fails on s390 with "Read value != nux". This is because verifier rewrites a complete 32-bit bpf_sysctl.file_pos update to a partial update of the first 32 bits of 64-bit *bpf_sysctl_kern.ppos, which is not correct on big-endian systems. Fix by using an offset on big-endian systems. Ditto for bpf_sysctl.file_pos reads. Currently the test does not detect a problem there, since it expects to see 0, which it gets with high probability in error cases, so change it to seek to offset 3 and expect 3 in bpf_sysctl.file_pos. Fixes: e1550bfe0de4 ("bpf: Add file_pos field to bpf_sysctl ctx") Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com> Acked-by: Yonghong Song <yhs@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20190816105300.49035-1-iii@linux.ibm.com/
Diffstat (limited to 'include/linux/filter.h')
-rw-r--r--include/linux/filter.h8
1 files changed, 4 insertions, 4 deletions
diff --git a/include/linux/filter.h b/include/linux/filter.h
index 92c6e31fb008..2ce57645f3cd 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -749,14 +749,14 @@ bpf_ctx_narrow_access_ok(u32 off, u32 size, u32 size_default)
}
static inline u8
-bpf_ctx_narrow_load_shift(u32 off, u32 size, u32 size_default)
+bpf_ctx_narrow_access_offset(u32 off, u32 size, u32 size_default)
{
- u8 load_off = off & (size_default - 1);
+ u8 access_off = off & (size_default - 1);
#ifdef __LITTLE_ENDIAN
- return load_off * 8;
+ return access_off;
#else
- return (size_default - (load_off + size)) * 8;
+ return size_default - (access_off + size);
#endif
}