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linux: mips: Fix getdents64 fallback on mips64-n32

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GCC mainline shows the following error:

../sysdeps/unix/sysv/linux/mips/mips64/getdents64.c: In function '__getdents64':
../sysdeps/unix/sysv/linux/mips/mips64/getdents64.c:121:7: error: 'memcpy' forming offset [4, 7] is out of the bounds [0, 4] [-Werror=array-bounds]
  121 |       memcpy (((char *) dp + offsetof (struct dirent64, d_ino)),
      |       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  122 |               KDP_MEMBER (kdp, d_ino), sizeof ((struct dirent64){0}.d_ino));
      |               ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../sysdeps/unix/sysv/linux/mips/mips64/getdents64.c:123:7: error: 'memcpy' forming offset [4, 7] is out of the bounds [0, 4] [-Werror=array-bounds]
  123 |       memcpy (((char *) dp + offsetof (struct dirent64, d_off)),
      |       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  124 |               KDP_MEMBER (kdp, d_off), sizeof ((struct dirent64){0}.d_off));
      |               ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The issue is due both d_ino and d_off fields for mips64-n32
kernel_dirent are 32-bits, while this is using memcpy to copy 64 bits
from it into the glibc dirent64.

The fix is to use a temporary buffer to read the correct type
from kernel_dirent.

Checked with a build-many-glibcs.py for mips64el-linux-gnu and I
also checked the tst-getdents64 on mips64el 4.1.4 kernel with
and without fallback enabled (by manually setting the
getdents64_supported).
This commit is contained in:
Adhemerval Zanella 2020-11-16 16:52:36 -03:00
parent 5f478eb0fb
commit 42d6270439
2 changed files with 42 additions and 24 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

37
sysdeps/unix/sysv/linux/mips/mips64/getdents64.c
View File

@ -90,17 +90,14 @@ __getdents64 (int fd, void *buf, size_t nbytes)
while ((char *) kdp < (char *) skdp + r)
{
/* This macro is used to avoid aliasing violation. */
#define KDP_MEMBER(src, member) \
(__typeof__((struct kernel_dirent){0}.member) *) \
memcpy (&((__typeof__((struct kernel_dirent){0}.member)){0}), \
((char *)(src) + offsetof (struct kernel_dirent, member)),\
sizeof ((struct kernel_dirent){0}.member))
/* This is a conservative approximation, since some of size_diff might
fit into the existing padding for alignment. */
unsigned short int k_reclen = *KDP_MEMBER (kdp, d_reclen);
unsigned short int new_reclen = ALIGN_UP (k_reclen + size_diff,
/* Obtain the d_ino, d_off, and d_reclen from kernel filled buffer. */
struct kernel_dirent kdirent;
memcpy (&kdirent, kdp, offsetof (struct kernel_dirent, d_name));
unsigned short int new_reclen = ALIGN_UP (kdirent.d_reclen + size_diff,
_Alignof (struct dirent64));
if (nb + new_reclen > nbytes)
{
@ -118,19 +115,21 @@ __getdents64 (int fd, void *buf, size_t nbytes)
}
nb += new_reclen;
memcpy (((char *) dp + offsetof (struct dirent64, d_ino)),
KDP_MEMBER (kdp, d_ino), sizeof ((struct dirent64){0}.d_ino));
memcpy (((char *) dp + offsetof (struct dirent64, d_off)),
KDP_MEMBER (kdp, d_off), sizeof ((struct dirent64){0}.d_off));
last_offset = *KDP_MEMBER (kdp, d_off);
memcpy (((char *) dp + offsetof (struct dirent64, d_reclen)),
&new_reclen, sizeof (new_reclen));
dp->d_type = *((char *) kdp + k_reclen - 1);
struct dirent64 d64;
d64.d_ino = kdirent.d_ino;
d64.d_off = kdirent.d_off;
d64.d_reclen = new_reclen;
d64.d_type = *((char *) kdp + kdirent.d_reclen - 1);
/* First copy only the header. */
memcpy (dp, &d64, offsetof (struct dirent64, d_name));
/* And then the d_name. */
memcpy (dp->d_name, kdp->d_name,
k_reclen - offsetof (struct kernel_dirent, d_name));
kdirent.d_reclen - offsetof (struct kernel_dirent, d_name));
last_offset = kdirent.d_off;
dp = (struct dirent64 *) ((char *) dp + new_reclen);
kdp = (struct kernel_dirent *) (((char *) kdp) + k_reclen);
kdp = (struct kernel_dirent *) (((char *) kdp) + kdirent.d_reclen);
}
return (char *) dp - (char *) buf;

29
sysdeps/unix/sysv/linux/tst-getdents64.c
View File

@ -76,8 +76,18 @@ large_buffer_checks (int fd)
}
}
static int
do_test (void)
static void
do_test_large_size (void)
{
int fd = xopen (".", O_RDONLY | O_DIRECTORY, 0);
TEST_VERIFY (fd >= 0);
large_buffer_checks (fd);
xclose (fd);
}
static void
do_test_by_size (size_t buffer_size)
{
/* The test compares the iteration order with readdir64. */
DIR *reference = opendir (".");
@ -98,7 +108,7 @@ do_test (void)
non-existing data. */
struct
{
char buffer[1024];
char buffer[buffer_size];
struct dirent64 pad;
} data;
@ -153,10 +163,19 @@ do_test (void)
rewinddir (reference);
}
large_buffer_checks (fd);
xclose (fd);
closedir (reference);
}
static int
do_test (void)
{
do_test_by_size (512);
do_test_by_size (1024);
do_test_by_size (4096);
do_test_large_size ();
return 0;
}