| Message ID | ZR9l446ndB4n1Xl4@gondor.apana.org.au (mailing list archive) |
|---|---|
| State | Accepted |
| Delegated to: | Herbert Xu |
| Headers | show |
| Series | dm crypt: Fix reqsize in crypt_iv_eboiv_gen | expand |
On Thu, Oct 05 2023 at 9:41P -0400, Herbert Xu <herbert@gondor.apana.org.au> wrote: > On Fri, Oct 06, 2023 at 08:04:18AM +0700, Bagas Sanjaya wrote: > > > > > Git bisect lead me to: > > > # first bad commit: [e3023094dffb41540330fb0c74cd3a019cd525c2] dm crypt: > > > Avoid using MAX_CIPHER_BLOCKSIZE > > > > > > If I git revert e3023094dffb41540330fb0c74cd3a019cd525c2 on current Linus' > > > git master, the issue goes away. So I'm personally not all that affected > > > anymore (if I'm ready to compile my kernels from now on), and I understand > > > that you have no clear way to reproduce this as it seems strongly bound to > > > hardware, but seems like this could point to a potentially serious security > > > issue since it involves both crypto and undefined behaviour. > > Thanks for the report. Sorry this is indeed my fault. The allocated > buffer is too small as it's missing the size for the request object > itself. > > Mike, would you be OK with me picking this fix up and pushing it to > Linus? > > Cheers, > > ---8<--- > A skcipher_request object is made up of struct skcipher_request > followed by a variable-sized trailer. The allocation of the > skcipher_request and IV in crypt_iv_eboiv_gen is missing the > memory for struct skcipher_request. Fix it by adding it to > reqsize. > > Fixes: e3023094dffb ("dm crypt: Avoid using MAX_CIPHER_BLOCKSIZE") > Reported-by: Tatu Heikkil� <tatu.heikkila@gmail.com> > Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> > > diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c > index f2662c21a6df..5315fd261c23 100644 > --- a/drivers/md/dm-crypt.c > +++ b/drivers/md/dm-crypt.c > @@ -753,7 +753,8 @@ static int crypt_iv_eboiv_gen(struct crypt_config *cc, u8 *iv, > int err; > u8 *buf; > > - reqsize = ALIGN(crypto_skcipher_reqsize(tfm), __alignof__(__le64)); > + reqsize = sizeof(*req) + crypto_skcipher_reqsize(tfm); > + reqsize = ALIGN(reqsize, __alignof__(__le64)); > > req = kmalloc(reqsize + cc->iv_size, GFP_NOIO); > if (!req) Sure, please do. Shouldn't your header Cc: stable given that the Fixes commit implies v6.5 needs this fix? (sorry I missed this the first time I 'Reviewed-by' the original commit) Reviewed-by: Mike Mike Snitzer <snitzer@kernel.org> Thanks, Mike
On Thu, Oct 05, 2023 at 10:26:14PM -0400, Mike Snitzer wrote: > > Sure, please do. Shouldn't your header Cc: stable given that the > Fixes commit implies v6.5 needs this fix? Sure I'll add it although it will be picked up automatically due to the Fixes header. I'll also fix the reporter's name. > Reviewed-by: Mike Mike Snitzer <snitzer@kernel.org> Thanks!
On 06.10.23 04:33, Herbert Xu wrote: > On Thu, Oct 05, 2023 at 10:26:14PM -0400, Mike Snitzer wrote: BTW, Herbert, thx for taking care of this quickly! >> Sure, please do. Shouldn't your header Cc: stable given that the >> Fixes commit implies v6.5 needs this fix? > > Sure I'll add it although it will be picked up automatically due > to the Fixes header. FWIW, as some people don't know this: that might be the case, but there is no guarantee, hence it's better to add it: https://lore.kernel.org/all/2023060703-colony-shakily-3514@gregkh/ > I'll also fix the reporter's name. Side note: a Link: or Closes: tag to the report (https://lore.kernel.org/all/f1b8d8f5-2079-537e-9d0f-d58da166fe50@gmail.com/ ) would be nice as well. Thx again. Ciao, Thorsten
On Fri, Oct 06, 2023 at 09:41:55 +0800, Herbert Xu wrote: > > On Fri, Oct 06, 2023 at 08:04:18AM +0700, Bagas Sanjaya wrote: > > > > > Git bisect lead me to: > > > # first bad commit: [e3023094dffb41540330fb0c74cd3a019cd525c2] dm crypt: > > > Avoid using MAX_CIPHER_BLOCKSIZE > > > > > > If I git revert e3023094dffb41540330fb0c74cd3a019cd525c2 on current Linus' > > > git master, the issue goes away. So I'm personally not all that affected > > > anymore (if I'm ready to compile my kernels from now on), and I understand > > > that you have no clear way to reproduce this as it seems strongly bound to > > > hardware, but seems like this could point to a potentially serious security > > > issue since it involves both crypto and undefined behaviour. > > Thanks for the report. Sorry this is indeed my fault. The allocated > buffer is too small as it's missing the size for the request object > itself. Thank you for your prompt fix, I can access the volume without issue now. :-) -Tatu
diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c index f2662c21a6df..5315fd261c23 100644 --- a/drivers/md/dm-crypt.c +++ b/drivers/md/dm-crypt.c @@ -753,7 +753,8 @@ static int crypt_iv_eboiv_gen(struct crypt_config *cc, u8 *iv, int err; u8 *buf; - reqsize = ALIGN(crypto_skcipher_reqsize(tfm), __alignof__(__le64)); + reqsize = sizeof(*req) + crypto_skcipher_reqsize(tfm); + reqsize = ALIGN(reqsize, __alignof__(__le64)); req = kmalloc(reqsize + cc->iv_size, GFP_NOIO); if (!req)