libbbb: find_mount_point() too eager to stat mounted devices
None of the below "devices" (first word on the line) are real.
sysfs /sys sysfs rw,nosuid,nodev,noexec,relatime 0 0
proc /proc proc rw,nosuid,nodev,noexec,relatime 0 0
devtmpfs /dev devtmpfs rw,nosuid,size=7917900k,nr_inodes=1979475,mode=755 0 0
tmpfs /dev/shm tmpfs rw,nosuid,nodev 0 0
devpts /dev/pts devpts rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 0 0
tmpfs /run tmpfs rw,nosuid,nodev,mode=755 0 0
pstore /sys/fs/pstore pstore rw,nosuid,nodev,noexec,relatime 0 0
configfs /sys/kernel/config configfs rw,relatime 0 0
tmpfs /tmp tmpfs rw,relatime 0 0
function old new delta
find_mount_point 297 302 +5
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/libbb/find_mount_point.c b/libbb/find_mount_point.c
index 94bbf1d..0e1be38 100644
--- a/libbb/find_mount_point.c
+++ b/libbb/find_mount_point.c
@@ -56,11 +56,22 @@
continue;
/* Is device's dev_t == name's dev_t? */
- if (stat(mountEntry->mnt_fsname, &s) == 0 && s.st_rdev == devno_of_name)
+ if (mountEntry->mnt_fsname[0] == '/'
+ /* ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+ * avoid stat'ing "sysfs", "proc", "none" and such,
+ * useless at best, can stat unrelated files at worst.
+ */
+ && stat(mountEntry->mnt_fsname, &s) == 0
+ && s.st_rdev == devno_of_name
+ ) {
break;
+ }
/* Match the directory's mount point. */
- if (stat(mountEntry->mnt_dir, &s) == 0 && s.st_dev == devno_of_name)
+ if (stat(mountEntry->mnt_dir, &s) == 0
+ && s.st_dev == devno_of_name
+ ) {
break;
+ }
}
endmntent(mtab_fp);