stat: fix inconsistency between struct stat and struct compat_stat

struct stat (defined in arch/x86/include/uapi/asm/stat.h) has 32-bit
st_dev and st_rdev; struct compat_stat (defined in
arch/x86/include/asm/compat.h) has 16-bit st_dev and st_rdev followed by
a 16-bit padding.

This patch fixes struct compat_stat to match struct stat.

[ Historical note: the old x86 'struct stat' did have that 16-bit field
  that the compat layer had kept around, but it was changes back in 2003
  by "struct stat - support larger dev_t":

    https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/?id=e95b2065677fe32512a597a79db94b77b90c968d

  and back in those days, the x86_64 port was still new, and separate
  from the i386 code, and had already picked up the old version with a
  16-bit st_dev field ]

Note that we can't change compat_dev_t because it is used by
compat_loop_info.

Also, if the st_dev and st_rdev values are 32-bit, we don't have to use
old_valid_dev to test if the value fits into them.  This fixes
-EOVERFLOW on filesystems that are on NVMe because NVMe uses the major
number 259.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: Andreas Schwab <schwab@linux-m68k.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/x86/include/asm/compat.h b/arch/x86/include/asm/compat.h
index 7516e4199b3c61cc90295a7506b52dff62183743..20fd0acd7d800b58a8b95b2ff807899af94cfae1 100644 (file)
--- a/arch/x86/include/asm/compat.h
+++ b/arch/x86/include/asm/compat.h
@@ -28,15 +28,13 @@ typedef u16         compat_ipc_pid_t;
 typedef __kernel_fsid_t        compat_fsid_t;
 
 struct compat_stat {
-       compat_dev_t    st_dev;
-       u16             __pad1;
+       u32             st_dev;
        compat_ino_t    st_ino;
        compat_mode_t   st_mode;
        compat_nlink_t  st_nlink;
        __compat_uid_t  st_uid;
        __compat_gid_t  st_gid;
-       compat_dev_t    st_rdev;
-       u16             __pad2;
+       u32             st_rdev;
        u32             st_size;
        u32             st_blksize;
        u32             st_blocks;

diff --git a/fs/stat.c b/fs/stat.c
index 7f734be0e57ec9f5d69927a672d7e4b20a4b006e..5c2c94464e8b0242430dc050f96678c35511509d 100644 (file)
--- a/fs/stat.c
+++ b/fs/stat.c
@@ -348,9 +348,6 @@ SYSCALL_DEFINE2(fstat, unsigned int, fd, struct __old_kernel_stat __user *, stat
 #  define choose_32_64(a,b) b
 #endif
 
-#define valid_dev(x)  choose_32_64(old_valid_dev(x),true)
-#define encode_dev(x) choose_32_64(old_encode_dev,new_encode_dev)(x)
-
 #ifndef INIT_STRUCT_STAT_PADDING
 #  define INIT_STRUCT_STAT_PADDING(st) memset(&st, 0, sizeof(st))
 #endif
@@ -359,7 +356,9 @@ static int cp_new_stat(struct kstat *stat, struct stat __user *statbuf)
 {
        struct stat tmp;
 
-       if (!valid_dev(stat->dev) || !valid_dev(stat->rdev))
+       if (sizeof(tmp.st_dev) < 4 && !old_valid_dev(stat->dev))
+               return -EOVERFLOW;
+       if (sizeof(tmp.st_rdev) < 4 && !old_valid_dev(stat->rdev))
                return -EOVERFLOW;
 #if BITS_PER_LONG == 32
        if (stat->size > MAX_NON_LFS)
@@ -367,7 +366,7 @@ static int cp_new_stat(struct kstat *stat, struct stat __user *statbuf)
 #endif
 
        INIT_STRUCT_STAT_PADDING(tmp);
-       tmp.st_dev = encode_dev(stat->dev);
+       tmp.st_dev = new_encode_dev(stat->dev);
        tmp.st_ino = stat->ino;
        if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
                return -EOVERFLOW;
@@ -377,7 +376,7 @@ static int cp_new_stat(struct kstat *stat, struct stat __user *statbuf)
                return -EOVERFLOW;
        SET_UID(tmp.st_uid, from_kuid_munged(current_user_ns(), stat->uid));
        SET_GID(tmp.st_gid, from_kgid_munged(current_user_ns(), stat->gid));
-       tmp.st_rdev = encode_dev(stat->rdev);
+       tmp.st_rdev = new_encode_dev(stat->rdev);
        tmp.st_size = stat->size;
        tmp.st_atime = stat->atime.tv_sec;
        tmp.st_mtime = stat->mtime.tv_sec;
@@ -665,11 +664,13 @@ static int cp_compat_stat(struct kstat *stat, struct compat_stat __user *ubuf)
 {
        struct compat_stat tmp;
 
-       if (!old_valid_dev(stat->dev) || !old_valid_dev(stat->rdev))
+       if (sizeof(tmp.st_dev) < 4 && !old_valid_dev(stat->dev))
+               return -EOVERFLOW;
+       if (sizeof(tmp.st_rdev) < 4 && !old_valid_dev(stat->rdev))
                return -EOVERFLOW;
 
        memset(&tmp, 0, sizeof(tmp));
-       tmp.st_dev = old_encode_dev(stat->dev);
+       tmp.st_dev = new_encode_dev(stat->dev);
        tmp.st_ino = stat->ino;
        if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
                return -EOVERFLOW;
@@ -679,7 +680,7 @@ static int cp_compat_stat(struct kstat *stat, struct compat_stat __user *ubuf)
                return -EOVERFLOW;
        SET_UID(tmp.st_uid, from_kuid_munged(current_user_ns(), stat->uid));
        SET_GID(tmp.st_gid, from_kgid_munged(current_user_ns(), stat->gid));
-       tmp.st_rdev = old_encode_dev(stat->rdev);
+       tmp.st_rdev = new_encode_dev(stat->rdev);
        if ((u64) stat->size > MAX_NON_LFS)
                return -EOVERFLOW;
        tmp.st_size = stat->size;