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Tsirkin" , Jason Wang , virtualization@lists.linux.dev, linux-kernel@vger.kernel.org References: <20260706100129.1541140-1-borntraeger@linux.ibm.com> <06b371e3-418c-41d8-8c06-1971cc24d8d4@linux.ibm.com> Content-Language: en-US From: Dragos Tatulea In-Reply-To: <06b371e3-418c-41d8-8c06-1971cc24d8d4@linux.ibm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-ClientProxiedBy: FR4P281CA0118.DEUP281.PROD.OUTLOOK.COM (2603:10a6:d10:bb::9) To CH3PR12MB8728.namprd12.prod.outlook.com (2603:10b6:610:171::12) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CH3PR12MB8728:EE_|CYXPR12MB9339:EE_ X-MS-Office365-Filtering-Correlation-Id: 61d2d8cf-3bd1-4b22-c320-08dedb597c6d X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: 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Borntraeger wrote: > > > Am 06.07.26 um 12:01 schrieb Christian Borntraeger: >> We have seen in our CI the following KASAN message: >> BUG: KASAN: slab-out-of-bounds in cmd_exec+0x550/0xca0 [mlx5_core] >> Read of size 272 at addr 0000000176795020 by task qemu-system-s39/82764 >> [...] >> [<000011388ab3a7a0>] cmd_exec+0x550/0xca0 [mlx5_core] >> [<000011388ab3b61c>] mlx5_cmd_exec_cb+0x25c/0x4f0 [mlx5_core] >> [<000011388b21e82e>] mlx5_vdpa_exec_async_cmds+0x22e/0x5e0 [mlx5_vdpa] >> [<000011388b21fd44>] create_direct_keys+0x954/0xef0 [mlx5_vdpa] >> [...] >> The buggy address is located 4128 bytes inside of >> allocated 4384-byte region [0000000176794000, 0000000176795120) >> >> So in essence we read 16 bytes beyond 4384-byte allocation. >> create_direct_keys calculates the pointer and length for in and out >> buffers. >> The size calculation for in includes the entire structure >> size (out + in + mtt[]) but the pointer passed to cmd_exec points only >> to the 'in' field, skipping the 'out' field. >> >> This causes mlx5_copy_to_msg() to read beyond the allocated buffer >> by sizeof(out) bytes when copying command data. >> >> Calculates the input size as sizeof(in) + mtt_array_size to match the >> pointer and allocation size. >> >> Fixes: 0071b138d44a ("vdpa/mlx5: Create direct MKEYs in parallel") >> Signed-off-by: Christian Borntraeger >> --- >> drivers/vdpa/mlx5/core/mr.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/vdpa/mlx5/core/mr.c b/drivers/vdpa/mlx5/core/mr.c >> index 6d02ccf9eb91..03fe7f5ca412 100644 >> --- a/drivers/vdpa/mlx5/core/mr.c >> +++ b/drivers/vdpa/mlx5/core/mr.c >> @@ -233,7 +233,7 @@ static int create_direct_keys(struct mlx5_vdpa_dev *mvdev, struct mlx5_vdpa_mr * >> cmds[i].out = cmd_mem->out; >> cmds[i].outlen = sizeof(cmd_mem->out); >> cmds[i].in = cmd_mem->in; >> - cmds[i].inlen = struct_size(cmd_mem, mtt, mttcount); >> + cmds[i].inlen = sizeof(cmd_mem->in) + (mttcount * sizeof(cmd_mem->mtt[0])); Woops... Thanks for the catch. The fix is good. > > Assuming the fix is the correct fix, question is, if I should use the offset of in instead, e.g. > > cmds[i].inlen = struct_size(cmd_mem, mtt, mttcount) - offsetof(cmd_mem, in); > > to handle potential alignment and padding aspects. > Seems harder to read. Why not: sizeof(cmd_mem->in) + flex_array_size(cmd_mem, mtts, mttcount) ? Thanks, Dragos