[PATCH 6.4 125/800] bpftool: JIT limited misreported as negative value on aarch64

Greg Kroah-Hartman
2023-07-16T19:58:38Z

From: Alan Maguire <alan.maguire@oracle.com>

[ Upstream commit 04cb8453a91c7c22f60ddadb6cef0d19abb33bb5 ]

On aarch64, "bpftool feature" reports an incorrect BPF JIT limit:

$ sudo /sbin/bpftool feature
Scanning system configuration...
bpf() syscall restricted to privileged users
JIT compiler is enabled
JIT compiler hardening is disabled
JIT compiler kallsyms exports are enabled for root
skipping kernel config, can't open file: No such file or directory
Global memory limit for JIT compiler for unprivileged users is -201326592 bytes

This is because /proc/sys/net/core/bpf_jit_limit reports

$ sudo cat /proc/sys/net/core/bpf_jit_limit
68169519595520

...and an int is assumed in read_procfs(). Change read_procfs()
to return a long to avoid negative value reporting.

Fixes: 7a4522bbef0c ("tools: bpftool: add probes for /proc/ eBPF parameters")
Reported-by: Nicky Veitch <nicky.veitch@oracle.com>
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20230512113134.58996-1-alan.maguire@oracle.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/bpf/bpftool/feature.c | 24 ++++++++++++------------
1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/tools/bpf/bpftool/feature.c b/tools/bpf/bpftool/feature.c
index da16e6a27cccd..0675d6a464138 100644
--- a/tools/bpf/bpftool/feature.c
+++ b/tools/bpf/bpftool/feature.c
@@ -167,12 +167,12 @@ static int get_vendor_id(int ifindex)
return strtol(buf, NULL, 0);
}

-static int read_procfs(const char *path)
+static long read_procfs(const char *path)
{
char *endptr, *line = NULL;
size_t len = 0;
FILE *fd;
- int res;
+ long res;

fd = fopen(path, "r");
if (!fd)
@@ -194,7 +194,7 @@ static int read_procfs(const char *path)

static void probe_unprivileged_disabled(void)
{
- int res;
+ long res;

/* No support for C-style ouptut */

@@ -216,14 +216,14 @@ static void probe_unprivileged_disabled(void)
printf("Unable to retrieve required privileges for bpf() syscall\n");
break;
default:
- printf("bpf() syscall restriction has unknown value %d\n", res);
+ printf("bpf() syscall restriction has unknown value %ld\n", res);
}
}
}

static void probe_jit_enable(void)
{
- int res;
+ long res;

/* No support for C-style ouptut */

@@ -245,7 +245,7 @@ static void probe_jit_enable(void)
printf("Unable to retrieve JIT-compiler status\n");
break;
default:
- printf("JIT-compiler status has unknown value %d\n",
+ printf("JIT-compiler status has unknown value %ld\n",
res);
}
}
@@ -253,7 +253,7 @@ static void probe_jit_enable(void)

static void probe_jit_harden(void)
{
- int res;
+ long res;

/* No support for C-style ouptut */

@@ -275,7 +275,7 @@ static void probe_jit_harden(void)
printf("Unable to retrieve JIT hardening status\n");
break;
default:
- printf("JIT hardening status has unknown value %d\n",
+ printf("JIT hardening status has unknown value %ld\n",
res);
}
}
@@ -283,7 +283,7 @@ static void probe_jit_harden(void)

static void probe_jit_kallsyms(void)
{
- int res;
+ long res;

/* No support for C-style ouptut */

@@ -302,14 +302,14 @@ static void probe_jit_kallsyms(void)
printf("Unable to retrieve JIT kallsyms export status\n");
break;
default:
- printf("JIT kallsyms exports status has unknown value %d\n", res);
+ printf("JIT kallsyms exports status has unknown value %ld\n", res);
}
}
}

static void probe_jit_limit(void)
{
- int res;
+ long res;

/* No support for C-style ouptut */

@@ -322,7 +322,7 @@ static void probe_jit_limit(void)
printf("Unable to retrieve global memory limit for JIT compiler for unprivileged users\n");
break;
default:
- printf("Global memory limit for JIT compiler for unprivileged users is %d bytes\n", res);
+ printf("Global memory limit for JIT compiler for unprivileged users is %ld bytes\n", res);
}
}
}
--
2.39.2