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libbbb: find_mount_point() too eager to stat mounted devices

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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>
This commit is contained in:
Denys Vlasenko 2019-04-29 17:59:08 +02:00
parent fa8878bf1f
commit f3a064f495
1 changed files with 13 additions and 2 deletions
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15
libbb/find_mount_point.c
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@ -56,12 +56,23 @@ struct mntent* FAST_FUNC find_mount_point(const char *name, int subdir_too)
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);
return mountEntry;