This is a note to let you know that I've just added the patch titled
fs: use UB-safe check for signed addition overflow in remap_verify_area
to the 6.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
fs-use-ub-safe-check-for-signed-addition-overflow-in.patch
and it can be found in the queue-6.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 57ad500c7370bffc4a9b9dd2f8148caf71cfdbf2
Author: David Sterba <dsterba@xxxxxxxx>
Date: Tue May 23 18:26:28 2023 +0200
fs: use UB-safe check for signed addition overflow in remap_verify_area
[ Upstream commit b7a9a503c38d665c05a789132b632d81ec0b2703 ]
The following warning pops up with enabled UBSAN in tests fstests/generic/303:
[23127.529395] UBSAN: Undefined behaviour in fs/read_write.c:1725:7
[23127.529400] signed integer overflow:
[23127.529403] 4611686018427322368 + 9223372036854775807 cannot be represented in type 'long long int'
[23127.529412] CPU: 4 PID: 26180 Comm: xfs_io Not tainted 5.2.0-rc2-1.ge195904-vanilla+ #450
[23127.556999] Hardware name: empty empty/S3993, BIOS PAQEX0-3 02/24/2008
[23127.557001] Call Trace:
[23127.557060] dump_stack+0x67/0x9b
[23127.557070] ubsan_epilogue+0x9/0x40
[23127.573496] handle_overflow+0xb3/0xc0
[23127.573514] do_clone_file_range+0x28f/0x2a0
[23127.573547] vfs_clone_file_range+0x35/0xb0
[23127.573564] ioctl_file_clone+0x8d/0xc0
[23127.590144] do_vfs_ioctl+0x300/0x700
[23127.590160] ksys_ioctl+0x70/0x80
[23127.590203] ? trace_hardirqs_off_thunk+0x1a/0x1c
[23127.590210] __x64_sys_ioctl+0x16/0x20
[23127.590215] do_syscall_64+0x5c/0x1d0
[23127.590224] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[23127.590231] RIP: 0033:0x7ff6d7250327
[23127.590241] RSP: 002b:00007ffe3a38f1d8 EFLAGS: 00000206 ORIG_RAX: 0000000000000010
[23127.590246] RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00007ff6d7250327
[23127.590249] RDX: 00007ffe3a38f220 RSI: 000000004020940d RDI: 0000000000000003
[23127.590252] RBP: 0000000000000000 R08: 00007ffe3a3c80a0 R09: 00007ffe3a3c8080
[23127.590255] R10: 000000000fa99fa0 R11: 0000000000000206 R12: 0000000000000000
[23127.590260] R13: 0000000000000000 R14: 3fffffffffff0000 R15: 00007ff6d750a20c
As loff_t is a signed type, we should use the safe overflow checks
instead of relying on compiler implementation.
The bogus values are intentional and the test is supposed to verify the
boundary conditions.
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
Message-Id: <20230523162628.17071-1-dsterba@xxxxxxxx>
Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/remap_range.c b/fs/remap_range.c
index 1331a890f2f29..87ae4f0dc3aa0 100644
--- a/fs/remap_range.c
+++ b/fs/remap_range.c
@@ -15,6 +15,7 @@
#include <linux/mount.h>
#include <linux/fs.h>
#include <linux/dax.h>
+#include <linux/overflow.h>
#include "internal.h"
#include <linux/uaccess.h>
@@ -101,10 +102,12 @@ static int generic_remap_checks(struct file *file_in, loff_t pos_in,
static int remap_verify_area(struct file *file, loff_t pos, loff_t len,
bool write)
{
+ loff_t tmp;
+
if (unlikely(pos < 0 || len < 0))
return -EINVAL;
- if (unlikely((loff_t) (pos + len) < 0))
+ if (unlikely(check_add_overflow(pos, len, &tmp)))
return -EINVAL;
return security_file_permission(file, write ? MAY_WRITE : MAY_READ);
