From: Mikulas Patocka <mpatocka@redhat.com> stable inclusion from stable-v5.10.209 commit c8c5311237448f6ffeecc9aec2362e3692623668 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/15577 CVE: CVE-2026-46294 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------------------------------------- commit 2fa49cc884f6496a915c35621ba4da35649bf159 upstream. Tony Asleson (using Claude) found a buffer overflow in dm-ioctl in the function retrieve_status: 1. The code in retrieve_status checks that the output string fits into the output buffer and writes the output string there 2. Then, the code aligns the "outptr" variable to the next 8-byte boundary: outptr = align_ptr(outptr); 3. The alignment doesn't check overflow, so outptr could point past the buffer end 4. The "for" loop is iterated again, it executes: remaining = len - (outptr - outbuf); 5. If "outptr" points past "outbuf + len", the arithmetics wraps around and the variable "remaining" contains unusually high number 6. With "remaining" being high, the code writes more data past the end of the buffer Luckily, this bug has no security implications because: 1. Only root can issue device mapper ioctls 2. The commonly used libraries that communicate with device mapper (libdevmapper and devicemapper-rs) use buffer size that is aligned to 8 bytes - thus, "outptr = align_ptr(outptr)" can't overshoot the input buffer and the bug can't happen accidentally Reported-by: Tony Asleson <tasleson@redhat.com> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Reviewed-by: Bryn M. Reeves <bmr@redhat.com> Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Lu Chentao <luchentao1@huawei.com> --- drivers/md/dm-ioctl.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c index ea519c4fa7b3..3bb9c0dced6e 100644 --- a/drivers/md/dm-ioctl.c +++ b/drivers/md/dm-ioctl.c @@ -1205,10 +1205,14 @@ static void retrieve_status(struct dm_table *table, outptr += l; used = param->data_start + (outptr - outbuf); outptr = align_ptr(outptr); + if (!outptr || outptr > outbuf + len) { + param->flags |= DM_BUFFER_FULL_FLAG; + break; + } spec->next = outptr - outbuf; } if (used) param->data_size = used; -- 2.52.0