bpf: fix verification error in bpf_execve_event #1454
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kkourt
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tpapagian
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olsajiri
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This patch fixes a verification error in a 4.18.0-477.21.1.el8_8.x86_64 kernel. The error was reported in issue 1442. The patch simplifies the code: it eliminates a common expression, and it changes some values from int to long to avoid generated code for the implicit casting. It also fixes a issue. bpf_probe_read_str may return 0, and in this case the old code will underflow. And even though we mask the size, the size value would have been wrong in this case: (gdb) printf "0x%zx\n", (0-1) & 0x7fff 0x7fff Signed-off-by: Kornilios Kourtis <kornilios@isovalent.com>
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This patch fixes a verification error in a 4.18.0-477.21.1.el8_8.x86_64 kernel.
The error was reported in issue #1442.
The patch simplifies the code: it eliminates a common expression, and it changes some values from int to long to avoid generated code for the implicit casting.
It also fixes a issue. bpf_probe_read_str may return 0, and in this case the old code will underflow. And even though we mask the size, the size value would have been wrong in this case:
(gdb) printf "0x%zx\n", (0-1) & 0x7fff
0x7fff