strlcpy() reads the entire source buffer first. This read may exceed
the destination size limit. This is both inefficient and can lead
to linear read overflows if a source string is not NUL-terminated[1].
Additionally, it returns the size of the source string, not the
resulting size of the destination string. In an effort to remove strlcpy()
completely[2], replace strlcpy() here with strscpy().
Overflow should be impossible here, but actually check for buffer sizes
being identical with BUILD_BUG_ON(), and include a run-time check as
well.
Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy [1]
Link: https://github.com/KSPP/linux/issues/89 [2]
Cc: "Martin K. Petersen" <[email protected]>
Cc: "James E.J. Bottomley" <[email protected]>
Cc: Steffen Maier <[email protected]>
Cc: Benjamin Block <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Vasily Gorbik <[email protected]>
Cc: Alexander Gordeev <[email protected]>
Cc: Christian Borntraeger <[email protected]>
Cc: Sven Schnelle <[email protected]>
Cc: Azeem Shaikh <[email protected]>
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Kees Cook <[email protected]>
---
v2:
- add BUILD_BUG_ON (bblock)
- CC SCSI maintainers (bblock)
v1: https://lore.kernel.org/all/[email protected]/
---
drivers/s390/scsi/zfcp_fc.c | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
diff --git a/drivers/s390/scsi/zfcp_fc.c b/drivers/s390/scsi/zfcp_fc.c
index 4f0d0e55f0d4..d6516ab00437 100644
--- a/drivers/s390/scsi/zfcp_fc.c
+++ b/drivers/s390/scsi/zfcp_fc.c
@@ -900,8 +900,19 @@ static void zfcp_fc_rspn(struct zfcp_adapter *adapter,
zfcp_fc_ct_ns_init(&rspn_req->ct_hdr, FC_NS_RSPN_ID,
FC_SYMBOLIC_NAME_SIZE);
hton24(rspn_req->rspn.fr_fid.fp_fid, fc_host_port_id(shost));
- len = strlcpy(rspn_req->rspn.fr_name, fc_host_symbolic_name(shost),
- FC_SYMBOLIC_NAME_SIZE);
+
+ BUILD_BUG_ON(sizeof(rspn_req->name) !=
+ sizeof(fc_host_symbolic_name(shost)));
+ BUILD_BUG_ON(sizeof(rspn_req->name) !=
+ type_max(typeof(rspn_req->rspn.fr_name_len)) + 1);
+ len = strscpy(rspn_req->name, fc_host_symbolic_name(shost),
+ sizeof(rspn_req->name));
+ /*
+ * It should be impossible for this to truncate (see BUILD_BUG_ON()
+ * above), but be robust anyway.
+ */
+ if (WARN_ON(len < 0))
+ len = sizeof(rspn_req->name) - 1;
rspn_req->rspn.fr_name_len = len;
sg_init_one(&fc_req->sg_req, rspn_req, sizeof(*rspn_req));
--
2.34.1
Hello Kees, Martin, James,
On Thu, Nov 30, 2023 at 12:41:00PM -0800, Kees Cook wrote:
> strlcpy() reads the entire source buffer first. This read may exceed
> the destination size limit. This is both inefficient and can lead
> to linear read overflows if a source string is not NUL-terminated[1].
> Additionally, it returns the size of the source string, not the
> resulting size of the destination string. In an effort to remove strlcpy()
> completely[2], replace strlcpy() here with strscpy().
>
> Overflow should be impossible here, but actually check for buffer sizes
> being identical with BUILD_BUG_ON(), and include a run-time check as
> well.
>
> Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy [1]
> Link: https://github.com/KSPP/linux/issues/89 [2]
> ---
> drivers/s390/scsi/zfcp_fc.c | 15 +++++++++++++--
> 1 file changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/s390/scsi/zfcp_fc.c b/drivers/s390/scsi/zfcp_fc.c
> index 4f0d0e55f0d4..d6516ab00437 100644
> --- a/drivers/s390/scsi/zfcp_fc.c
> +++ b/drivers/s390/scsi/zfcp_fc.c
> @@ -900,8 +900,19 @@ static void zfcp_fc_rspn(struct zfcp_adapter *adapter,
> zfcp_fc_ct_ns_init(&rspn_req->ct_hdr, FC_NS_RSPN_ID,
> FC_SYMBOLIC_NAME_SIZE);
> hton24(rspn_req->rspn.fr_fid.fp_fid, fc_host_port_id(shost));
> - len = strlcpy(rspn_req->rspn.fr_name, fc_host_symbolic_name(shost),
> - FC_SYMBOLIC_NAME_SIZE);
> +
> + BUILD_BUG_ON(sizeof(rspn_req->name) !=
> + sizeof(fc_host_symbolic_name(shost)));
> + BUILD_BUG_ON(sizeof(rspn_req->name) !=
> + type_max(typeof(rspn_req->rspn.fr_name_len)) + 1);
> + len = strscpy(rspn_req->name, fc_host_symbolic_name(shost),
> + sizeof(rspn_req->name));
> + /*
> + * It should be impossible for this to truncate (see BUILD_BUG_ON()
> + * above), but be robust anyway.
> + */
> + if (WARN_ON(len < 0))
> + len = sizeof(rspn_req->name) - 1;
Looks good to me.
Acked-by: Benjamin Block <[email protected]>
> rspn_req->rspn.fr_name_len = len;
Martin, James, can you please pick this up for the v6.8 queue?
--
Best Regards, Benjamin Block / Linux on IBM Z Kernel Development
IBM Deutschland Research & Development GmbH / https://www.ibm.com/privacy
Vors. Aufs.-R.: Gregor Pillen / Gesch?ftsf?hrung: David Faller
Sitz der Ges.: B?blingen / Registergericht: AmtsG Stuttgart, HRB 243294
Kees,
> strlcpy() reads the entire source buffer first. This read may exceed
> the destination size limit. This is both inefficient and can lead to
> linear read overflows if a source string is not NUL-terminated[1].
> Additionally, it returns the size of the source string, not the
> resulting size of the destination string. In an effort to remove
> strlcpy() completely[2], replace strlcpy() here with strscpy().
Applied to 6.8/scsi-staging, thanks!
--
Martin K. Petersen Oracle Linux Engineering
On Thu, 30 Nov 2023 12:41:00 -0800, Kees Cook wrote:
> strlcpy() reads the entire source buffer first. This read may exceed
> the destination size limit. This is both inefficient and can lead
> to linear read overflows if a source string is not NUL-terminated[1].
> Additionally, it returns the size of the source string, not the
> resulting size of the destination string. In an effort to remove strlcpy()
> completely[2], replace strlcpy() here with strscpy().
>
> [...]
Applied to 6.8/scsi-queue, thanks!
[1/1] scsi: zfcp: Replace strlcpy() with strscpy()
https://git.kernel.org/mkp/scsi/c/0d224b1088af
--
Martin K. Petersen Oracle Linux Engineering