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linux: mips: Fix getdents64 fallback on mips64-n32
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).
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@ -90,17 +90,14 @@ __getdents64 (int fd, void *buf, size_t nbytes)
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while ((char *) kdp < (char *) skdp + r)
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{
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/* This macro is used to avoid aliasing violation. */
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#define KDP_MEMBER(src, member) \
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(__typeof__((struct kernel_dirent){0}.member) *) \
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memcpy (&((__typeof__((struct kernel_dirent){0}.member)){0}), \
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((char *)(src) + offsetof (struct kernel_dirent, member)),\
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sizeof ((struct kernel_dirent){0}.member))
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/* This is a conservative approximation, since some of size_diff might
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fit into the existing padding for alignment. */
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unsigned short int k_reclen = *KDP_MEMBER (kdp, d_reclen);
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unsigned short int new_reclen = ALIGN_UP (k_reclen + size_diff,
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/* Obtain the d_ino, d_off, and d_reclen from kernel filled buffer. */
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struct kernel_dirent kdirent;
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memcpy (&kdirent, kdp, offsetof (struct kernel_dirent, d_name));
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unsigned short int new_reclen = ALIGN_UP (kdirent.d_reclen + size_diff,
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_Alignof (struct dirent64));
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if (nb + new_reclen > nbytes)
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{
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@ -118,19 +115,21 @@ __getdents64 (int fd, void *buf, size_t nbytes)
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}
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nb += new_reclen;
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memcpy (((char *) dp + offsetof (struct dirent64, d_ino)),
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KDP_MEMBER (kdp, d_ino), sizeof ((struct dirent64){0}.d_ino));
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memcpy (((char *) dp + offsetof (struct dirent64, d_off)),
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KDP_MEMBER (kdp, d_off), sizeof ((struct dirent64){0}.d_off));
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last_offset = *KDP_MEMBER (kdp, d_off);
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memcpy (((char *) dp + offsetof (struct dirent64, d_reclen)),
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&new_reclen, sizeof (new_reclen));
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dp->d_type = *((char *) kdp + k_reclen - 1);
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struct dirent64 d64;
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d64.d_ino = kdirent.d_ino;
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d64.d_off = kdirent.d_off;
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d64.d_reclen = new_reclen;
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d64.d_type = *((char *) kdp + kdirent.d_reclen - 1);
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/* First copy only the header. */
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memcpy (dp, &d64, offsetof (struct dirent64, d_name));
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/* And then the d_name. */
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memcpy (dp->d_name, kdp->d_name,
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k_reclen - offsetof (struct kernel_dirent, d_name));
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kdirent.d_reclen - offsetof (struct kernel_dirent, d_name));
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last_offset = kdirent.d_off;
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dp = (struct dirent64 *) ((char *) dp + new_reclen);
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kdp = (struct kernel_dirent *) (((char *) kdp) + k_reclen);
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kdp = (struct kernel_dirent *) (((char *) kdp) + kdirent.d_reclen);
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}
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return (char *) dp - (char *) buf;
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@ -76,8 +76,18 @@ large_buffer_checks (int fd)
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}
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}
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static int
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do_test (void)
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static void
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do_test_large_size (void)
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{
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int fd = xopen (".", O_RDONLY | O_DIRECTORY, 0);
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TEST_VERIFY (fd >= 0);
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large_buffer_checks (fd);
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xclose (fd);
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}
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static void
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do_test_by_size (size_t buffer_size)
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{
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/* The test compares the iteration order with readdir64. */
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DIR *reference = opendir (".");
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@ -98,7 +108,7 @@ do_test (void)
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non-existing data. */
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struct
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{
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char buffer[1024];
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char buffer[buffer_size];
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struct dirent64 pad;
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} data;
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@ -153,10 +163,19 @@ do_test (void)
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rewinddir (reference);
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}
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large_buffer_checks (fd);
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xclose (fd);
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closedir (reference);
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}
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static int
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do_test (void)
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{
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do_test_by_size (512);
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do_test_by_size (1024);
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do_test_by_size (4096);
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do_test_large_size ();
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return 0;
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}
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