| Message ID | 20230831143638.232596-1-azeemshaikh38@gmail.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v3] scsi: target: Replace strlcpy with strscpy | expand |
On Thu, Aug 31, 2023 at 02:36:38PM +0000, Azeem Shaikh 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]. > In an effort to remove strlcpy() completely [2], replace > strlcpy() here with strscpy(). > > Direct replacement is safe here since return value of -errno > is used to check for truncation instead of sizeof(dest). > > [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy > [2] https://github.com/KSPP/linux/issues/89 > > Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com> > --- > v3: > * Address readability comment. > > v2: > * Replace all instances of strlcpy in this file instead of just 1. > * https://lore.kernel.org/all/20230830210724.4156575-1-azeemshaikh38@gmail.com/ > > v1: > * https://lore.kernel.org/all/20230830200717.4129442-1-azeemshaikh38@gmail.com/ > > drivers/target/target_core_configfs.c | 24 ++++++++++++------------ > 1 file changed, 12 insertions(+), 12 deletions(-) > > diff --git a/drivers/target/target_core_configfs.c b/drivers/target/target_core_configfs.c > index 936e5ff1b209..d5860c1c1f46 100644 > --- a/drivers/target/target_core_configfs.c > +++ b/drivers/target/target_core_configfs.c > @@ -1392,16 +1392,16 @@ static ssize_t target_wwn_vendor_id_store(struct config_item *item, > /* +2 to allow for a trailing (stripped) '\n' and null-terminator */ > unsigned char buf[INQUIRY_VENDOR_LEN + 2]; > char *stripped = NULL; > - size_t len; > + ssize_t len; > ssize_t ret; > > - len = strlcpy(buf, page, sizeof(buf)); > - if (len < sizeof(buf)) { > + len = strscpy(buf, page, sizeof(buf)); > + if (len > 0) { > /* Strip any newline added from userspace. */ > stripped = strstrip(buf); > len = strlen(stripped); > } > - if (len > INQUIRY_VENDOR_LEN) { > + if (len < 0 || len > INQUIRY_VENDOR_LEN) { Agh, sorry I missed this before: the first "if" needs to be "len >= 0" otherwise this: ret = target_check_inquiry_data(stripped); will be passing a NULL pointer...
On Thu, Aug 31, 2023 at 2:42 PM Kees Cook <keescook@chromium.org> wrote: > > On Thu, Aug 31, 2023 at 02:36:38PM +0000, Azeem Shaikh 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]. > > In an effort to remove strlcpy() completely [2], replace > > strlcpy() here with strscpy(). > > > > Direct replacement is safe here since return value of -errno > > is used to check for truncation instead of sizeof(dest). > > > > [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy > > [2] https://github.com/KSPP/linux/issues/89 > > > > Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com> > > --- > > v3: > > * Address readability comment. > > > > v2: > > * Replace all instances of strlcpy in this file instead of just 1. > > * https://lore.kernel.org/all/20230830210724.4156575-1-azeemshaikh38@gmail.com/ > > > > v1: > > * https://lore.kernel.org/all/20230830200717.4129442-1-azeemshaikh38@gmail.com/ > > > > drivers/target/target_core_configfs.c | 24 ++++++++++++------------ > > 1 file changed, 12 insertions(+), 12 deletions(-) > > > > diff --git a/drivers/target/target_core_configfs.c b/drivers/target/target_core_configfs.c > > index 936e5ff1b209..d5860c1c1f46 100644 > > --- a/drivers/target/target_core_configfs.c > > +++ b/drivers/target/target_core_configfs.c > > @@ -1392,16 +1392,16 @@ static ssize_t target_wwn_vendor_id_store(struct config_item *item, > > /* +2 to allow for a trailing (stripped) '\n' and null-terminator */ > > unsigned char buf[INQUIRY_VENDOR_LEN + 2]; > > char *stripped = NULL; > > - size_t len; > > + ssize_t len; > > ssize_t ret; > > > > - len = strlcpy(buf, page, sizeof(buf)); > > - if (len < sizeof(buf)) { > > + len = strscpy(buf, page, sizeof(buf)); > > + if (len > 0) { > > /* Strip any newline added from userspace. */ > > stripped = strstrip(buf); > > len = strlen(stripped); > > } > > - if (len > INQUIRY_VENDOR_LEN) { > > + if (len < 0 || len > INQUIRY_VENDOR_LEN) { > > Agh, sorry I missed this before: the first "if" needs to be "len >= 0" > otherwise this: > > ret = target_check_inquiry_data(stripped); > > will be passing a NULL pointer... > Hmm, the current implementation of strscpy never returns 0. If sizeof(buf) is 0, it'll return -E2BIG. Do you still prefer that I update this to check for len >= 0?
On Thu, Aug 31, 2023 at 03:20:47PM -0400, Azeem Shaikh wrote: > On Thu, Aug 31, 2023 at 2:42 PM Kees Cook <keescook@chromium.org> wrote: > > > > On Thu, Aug 31, 2023 at 02:36:38PM +0000, Azeem Shaikh 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]. > > > In an effort to remove strlcpy() completely [2], replace > > > strlcpy() here with strscpy(). > > > > > > Direct replacement is safe here since return value of -errno > > > is used to check for truncation instead of sizeof(dest). > > > > > > [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy > > > [2] https://github.com/KSPP/linux/issues/89 > > > > > > Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com> > > > --- > > > v3: > > > * Address readability comment. > > > > > > v2: > > > * Replace all instances of strlcpy in this file instead of just 1. > > > * https://lore.kernel.org/all/20230830210724.4156575-1-azeemshaikh38@gmail.com/ > > > > > > v1: > > > * https://lore.kernel.org/all/20230830200717.4129442-1-azeemshaikh38@gmail.com/ > > > > > > drivers/target/target_core_configfs.c | 24 ++++++++++++------------ > > > 1 file changed, 12 insertions(+), 12 deletions(-) > > > > > > diff --git a/drivers/target/target_core_configfs.c b/drivers/target/target_core_configfs.c > > > index 936e5ff1b209..d5860c1c1f46 100644 > > > --- a/drivers/target/target_core_configfs.c > > > +++ b/drivers/target/target_core_configfs.c > > > @@ -1392,16 +1392,16 @@ static ssize_t target_wwn_vendor_id_store(struct config_item *item, > > > /* +2 to allow for a trailing (stripped) '\n' and null-terminator */ > > > unsigned char buf[INQUIRY_VENDOR_LEN + 2]; > > > char *stripped = NULL; > > > - size_t len; > > > + ssize_t len; > > > ssize_t ret; > > > > > > - len = strlcpy(buf, page, sizeof(buf)); > > > - if (len < sizeof(buf)) { > > > + len = strscpy(buf, page, sizeof(buf)); > > > + if (len > 0) { > > > /* Strip any newline added from userspace. */ > > > stripped = strstrip(buf); > > > len = strlen(stripped); > > > } > > > - if (len > INQUIRY_VENDOR_LEN) { > > > + if (len < 0 || len > INQUIRY_VENDOR_LEN) { > > > > Agh, sorry I missed this before: the first "if" needs to be "len >= 0" > > otherwise this: > > > > ret = target_check_inquiry_data(stripped); > > > > will be passing a NULL pointer... > > > > Hmm, the current implementation of strscpy never returns 0. If > sizeof(buf) is 0, it'll return -E2BIG. Do you still prefer that I > update this to check for len >= 0? Oh right! Nevermind, then. Fine as-is. :) Reviewed-by: Kees Cook <keescook@chromium.org>
Azeem, > 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]. In > an effort to remove strlcpy() completely [2], replace strlcpy() here > with strscpy(). Applied to 6.6/scsi-staging, thanks!
On Thu, 31 Aug 2023 14:36:38 +0000, Azeem Shaikh 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]. > In an effort to remove strlcpy() completely [2], replace > strlcpy() here with strscpy(). > > [...] Applied to 6.6/scsi-fixes, thanks! [1/1] scsi: target: Replace strlcpy with strscpy https://git.kernel.org/mkp/scsi/c/5c584fe6098a
diff --git a/drivers/target/target_core_configfs.c b/drivers/target/target_core_configfs.c index 936e5ff1b209..d5860c1c1f46 100644 --- a/drivers/target/target_core_configfs.c +++ b/drivers/target/target_core_configfs.c @@ -1392,16 +1392,16 @@ static ssize_t target_wwn_vendor_id_store(struct config_item *item, /* +2 to allow for a trailing (stripped) '\n' and null-terminator */ unsigned char buf[INQUIRY_VENDOR_LEN + 2]; char *stripped = NULL; - size_t len; + ssize_t len; ssize_t ret; - len = strlcpy(buf, page, sizeof(buf)); - if (len < sizeof(buf)) { + len = strscpy(buf, page, sizeof(buf)); + if (len > 0) { /* Strip any newline added from userspace. */ stripped = strstrip(buf); len = strlen(stripped); } - if (len > INQUIRY_VENDOR_LEN) { + if (len < 0 || len > INQUIRY_VENDOR_LEN) { pr_err("Emulated T10 Vendor Identification exceeds" " INQUIRY_VENDOR_LEN: " __stringify(INQUIRY_VENDOR_LEN) "\n"); @@ -1448,16 +1448,16 @@ static ssize_t target_wwn_product_id_store(struct config_item *item, /* +2 to allow for a trailing (stripped) '\n' and null-terminator */ unsigned char buf[INQUIRY_MODEL_LEN + 2]; char *stripped = NULL; - size_t len; + ssize_t len; ssize_t ret; - len = strlcpy(buf, page, sizeof(buf)); - if (len < sizeof(buf)) { + len = strscpy(buf, page, sizeof(buf)); + if (len > 0) { /* Strip any newline added from userspace. */ stripped = strstrip(buf); len = strlen(stripped); } - if (len > INQUIRY_MODEL_LEN) { + if (len < 0 || len > INQUIRY_MODEL_LEN) { pr_err("Emulated T10 Vendor exceeds INQUIRY_MODEL_LEN: " __stringify(INQUIRY_MODEL_LEN) "\n"); @@ -1504,16 +1504,16 @@ static ssize_t target_wwn_revision_store(struct config_item *item, /* +2 to allow for a trailing (stripped) '\n' and null-terminator */ unsigned char buf[INQUIRY_REVISION_LEN + 2]; char *stripped = NULL; - size_t len; + ssize_t len; ssize_t ret; - len = strlcpy(buf, page, sizeof(buf)); - if (len < sizeof(buf)) { + len = strscpy(buf, page, sizeof(buf)); + if (len > 0) { /* Strip any newline added from userspace. */ stripped = strstrip(buf); len = strlen(stripped); } - if (len > INQUIRY_REVISION_LEN) { + if (len < 0 || len > INQUIRY_REVISION_LEN) { pr_err("Emulated T10 Revision exceeds INQUIRY_REVISION_LEN: " __stringify(INQUIRY_REVISION_LEN) "\n");
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]. In an effort to remove strlcpy() completely [2], replace strlcpy() here with strscpy(). Direct replacement is safe here since return value of -errno is used to check for truncation instead of sizeof(dest). [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy [2] https://github.com/KSPP/linux/issues/89 Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com> --- v3: * Address readability comment. v2: * Replace all instances of strlcpy in this file instead of just 1. * https://lore.kernel.org/all/20230830210724.4156575-1-azeemshaikh38@gmail.com/ v1: * https://lore.kernel.org/all/20230830200717.4129442-1-azeemshaikh38@gmail.com/ drivers/target/target_core_configfs.c | 24 ++++++++++++------------ 1 file changed, 12 insertions(+), 12 deletions(-) -- 2.42.0.283.g2d96d420d3-goog