[PATCH 5.10 48/86] stat: fix inconsistency between struct stat and struct compat_stat

Greg Kroah-Hartman
2022-04-26T08:54:10Z

From: Mikulas Patocka <mpatocka@redhat.com>

[ Upstream commit 932aba1e169090357a77af18850a10c256b50819 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/x86/include/asm/compat.h | 6 ++----
fs/stat.c | 19 ++++++++++---------
2 files changed, 12 insertions(+), 13 deletions(-)

diff --git a/arch/x86/include/asm/compat.h b/arch/x86/include/asm/compat.h
index 0e327a01f50f..46a067bd7e0b 100644
--- a/arch/x86/include/asm/compat.h
+++ b/arch/x86/include/asm/compat.h
@@ -29,15 +29,13 @@ typedef u32 compat_caddr_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 1196af4d1ea0..04550c0ba540 100644
--- a/fs/stat.c
+++ b/fs/stat.c
@@ -306,9 +306,6 @@ 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
@@ -317,7 +314,9 @@ 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)
@@ -325,7 +324,7 @@ 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;
@@ -335,7 +334,7 @@ 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;
@@ -616,11 +615,13 @@ 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;
@@ -630,7 +631,7 @@ 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;
--
2.35.1