From: =?utf-8?q?Petr_=C5=A0tetiar?= Date: Thu, 22 Sep 2022 11:49:13 +0200 Subject: [PATCH 01/24] lib/path: ul_path_cpuparse: fix parsing of empty sysfs files MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Kernel 5.15 returns empty content for topology/thread_siblings on aarch64 platform, which in conjunction of uninitialized `buf` memory buffer results in the garbage: (gdb) p buf $14 = " @\377\367\177\000\000\000\275\000\347j\032\236" This garbage is then being later consumed by underlying helper functions like for example cpumask_parse() and this leads to the following crash later: in __libc_free (p=0x7ff7f67c00) at src/malloc/mallocng/free.c:105 in free (p=) at src/malloc/free.c:5 in add_cpuset_to_array (setsize=, set=, items=, ary=) at ../sys-utils/lscpu-topology.c:29 in cputype_read_topology (cxt=cxt@entry=0x7ff7fffe70, ct=0x4298a0) at ../sys-utils/lscpu-topology.c:153 in lscpu_read_topology (cxt=cxt@entry=0x7ff7fffe70) at ../sys-utils/lscpu-topology.c:629 in main (argc=1, argv=0x7ffffffdb8) at ../sys-utils/lscpu.c:1341 It looks like the problem is that current logic expects fgets() to set errno on failure, but fgets() is not documented to do so and and neither glibc nor musl set errno. So if errno was set to 0 before fgets() call, the failure from fgets() is ignored and then invalid buffer is being parsed. Fixes: #1810 Suggested-by: Thomas Weißschuh Signed-off-by: Petr Štetiar --- lib/path.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/lib/path.c b/lib/path.c index 42b4ead..8da6c06 100644 --- a/lib/path.c +++ b/lib/path.c @@ -1028,7 +1028,7 @@ static int ul_path_cpuparse(struct path_cxt *pc, cpu_set_t **set, int maxcpus, i if (!f) return -errno; - rc = fgets(buf, len, f) == NULL ? -errno : 0; + rc = fgets(buf, len, f) == NULL ? -EIO : 0; fclose(f); if (rc)