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Fix VFS2 getdents()/getdents64() alignment.

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PiperOrigin-RevId: 306263615
This commit is contained in:
Jamie Liu
2020-04-13 10:52:22 -07:00
committed by gVisor bot
parent ef0b5584e5
commit 445c366581
1 changed files with 16 additions and 4 deletions
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pkg/sentry/syscalls/linux/vfs2/getdents.go
+16 -4
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@@ -97,6 +97,7 @@ func (cb *getdentsCallback) Handle(dirent vfs.Dirent) error {
// char d_name[]; /* Filename (null-terminated) */
// };
size := 8 + 8 + 2 + 1 + 1 + len(dirent.Name)
size = (size + 7) &^ 7 // round up to multiple of 8
if size > cb.remaining {
return syserror.EINVAL
}
@@ -106,7 +107,12 @@ func (cb *getdentsCallback) Handle(dirent vfs.Dirent) error {
usermem.ByteOrder.PutUint16(buf[16:18], uint16(size))
buf[18] = dirent.Type
copy(buf[19:], dirent.Name)
buf[size-1] = 0 // NUL terminator
// Zero out all remaining bytes in buf, including the NUL terminator
// after dirent.Name.
bufTail := buf[19+len(dirent.Name):]
for i := range bufTail {
bufTail[i] = 0
}
} else {
// struct linux_dirent {
// unsigned long d_ino; /* Inode number */
@@ -125,6 +131,7 @@ func (cb *getdentsCallback) Handle(dirent vfs.Dirent) error {
panic(fmt.Sprintf("unsupported sizeof(unsigned long): %d", cb.t.Arch().Width()))
}
size := 8 + 8 + 2 + 1 + 1 + 1 + len(dirent.Name)
size = (size + 7) &^ 7 // round up to multiple of sizeof(long)
if size > cb.remaining {
return syserror.EINVAL
}
@@ -133,9 +140,14 @@ func (cb *getdentsCallback) Handle(dirent vfs.Dirent) error {
usermem.ByteOrder.PutUint64(buf[8:16], uint64(dirent.NextOff))
usermem.ByteOrder.PutUint16(buf[16:18], uint16(size))
copy(buf[18:], dirent.Name)
buf[size-3] = 0 // NUL terminator
buf[size-2] = 0 // zero padding byte
buf[size-1] = dirent.Type
// Zero out all remaining bytes in buf, including the NUL terminator
// after dirent.Name and the zero padding byte between the name and
// dirent type.
bufTail := buf[18+len(dirent.Name):]
for i := range bufTail {
bufTail[i] = 0
}
bufTail[2] = dirent.Type
}
n, err := cb.t.CopyOutBytes(cb.addr, buf)
if err != nil {