On Mon, 23 Jun 2025, Milan Broz wrote: > On 6/23/25 1:11 PM, Herbert Xu wrote: > > On Mon, Jun 23, 2025 at 11:40:39AM +0200, Mikulas Patocka wrote: > > > > > > 345 bytes on the stack - I think it's too much, given the fact that it > > > already uses 345 bytes (from SHASH_DESC_ON_STACK) and it may be called in > > > a tasklet context. I'd prefer a solution that allocates less bytes. > > > > > > I don't see the beginning of this thread, so I'd like to ask what's the > > > problem here, what algorithm other than md5 is used here that causes the > > > buffer overflow? > > > > The md5 export size has increased due to the partial block API > > thus triggering the overflow. > > > > How about this patch? OK. I accepted the patch and committed it to the linux-dm git. Mikulas > For v2: > > Tested-by: Milan Broz <gmazyland@xxxxxxxxx> > > Just for the context, the patch fixes OOPS on 32bit (but 64bit should overflow > struct too): > > : Oops: Oops: 0000 [#1] SMP > : CPU: 1 UID: 0 PID: 12 Comm: kworker/u16:0 Not tainted 6.16.0-rc2+ #993 > PREEMPT(full) > : Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference > Platform, BIOS 6.00 11/12/2020 > : Workqueue: kcryptd-254:0-1 kcryptd_crypt [dm_crypt] > : EIP: __crypto_shash_export+0xf/0x90 > : Code: 4a c1 c7 40 20 a0 b4 4a c1 81 cf 0e 00 04 08 89 78 50 e9 2b ff ff ff > 8d 74 26 00 55 89 e5 57 56 53 89 c3 89 d6 8b 00 8b 40 14 <8b> 50 fc f6 40 13 > 01 74 04 4a 2b 50 14 85 c9 74 10 89 f2 89 d8 ff > : EAX: 303a3435 EBX: c3007c90 ECX: 00000000 EDX: c3007c38 > : ESI: c3007c38 EDI: c3007c90 EBP: c3007bfc ESP: c3007bf0 > : DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 EFLAGS: 00010216 > : CR0: 80050033 CR2: 303a3431 CR3: 04fbe000 CR4: 00350e90 > : Call Trace: > : crypto_shash_export+0x65/0xc0 > : crypt_iv_lmk_one+0x106/0x1a0 [dm_crypt] > > ... > > The bisect was > > efd62c85525e212705368b24eb90ef10778190f5 is the first bad commit > commit efd62c85525e212705368b24eb90ef10778190f5 (HEAD) > Author: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> > Date: Fri Apr 18 10:59:04 2025 +0800 > > crypto: md5-generic - Use API partial block handling > > Use the Crypto API partial block handling. > > Milan >
