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Subject[PATCH 4.19 21/49] cifs: Fix incomplete memory allocation on setxattr path
Date
From: Vladimir Zapolskiy <vladimir@tuxera.com>

commit 64b7f674c292207624b3d788eda2dde3dc1415df upstream.

On setxattr() syscall path due to an apprent typo the size of a dynamically
allocated memory chunk for storing struct smb2_file_full_ea_info object is
computed incorrectly, to be more precise the first addend is the size of
a pointer instead of the wanted object size. Coincidentally it makes no
difference on 64-bit platforms, however on 32-bit targets the following
memcpy() writes 4 bytes of data outside of the dynamically allocated memory.

=============================================================================
BUG kmalloc-16 (Not tainted): Redzone overwritten
-----------------------------------------------------------------------------

Disabling lock debugging due to kernel taint
INFO: 0x79e69a6f-0x9e5cdecf @offset=368. First byte 0x73 instead of 0xcc
INFO: Slab 0xd36d2454 objects=85 used=51 fp=0xf7d0fc7a flags=0x35000201
INFO: Object 0x6f171df3 @offset=352 fp=0x00000000

Redzone 5d4ff02d: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc ................
Object 6f171df3: 00 00 00 00 00 05 06 00 73 6e 72 75 62 00 66 69 ........snrub.fi
Redzone 79e69a6f: 73 68 32 0a sh2.
Padding 56254d82: 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZ
CPU: 0 PID: 8196 Comm: attr Tainted: G B 5.9.0-rc8+ #3
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1 04/01/2014
Call Trace:
dump_stack+0x54/0x6e
print_trailer+0x12c/0x134
check_bytes_and_report.cold+0x3e/0x69
check_object+0x18c/0x250
free_debug_processing+0xfe/0x230
__slab_free+0x1c0/0x300
kfree+0x1d3/0x220
smb2_set_ea+0x27d/0x540
cifs_xattr_set+0x57f/0x620
__vfs_setxattr+0x4e/0x60
__vfs_setxattr_noperm+0x4e/0x100
__vfs_setxattr_locked+0xae/0xd0
vfs_setxattr+0x4e/0xe0
setxattr+0x12c/0x1a0
path_setxattr+0xa4/0xc0
__ia32_sys_lsetxattr+0x1d/0x20
__do_fast_syscall_32+0x40/0x70
do_fast_syscall_32+0x29/0x60
do_SYSENTER_32+0x15/0x20
entry_SYSENTER_32+0x9f/0xf2

Fixes: 5517554e4313 ("cifs: Add support for writing attributes on SMB2+")
Signed-off-by: Vladimir Zapolskiy <vladimir@tuxera.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/cifs/smb2ops.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -950,7 +950,7 @@ smb2_set_ea(const unsigned int xid, stru
return rc;
}

- len = sizeof(ea) + ea_name_len + ea_value_len + 1;
+ len = sizeof(*ea) + ea_name_len + ea_value_len + 1;
ea = kzalloc(len, GFP_KERNEL);
if (ea == NULL) {
SMB2_close(xid, tcon, fid.persistent_fid, fid.volatile_fid);

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