| Message ID | 20230830210724.4156575-1-azeemshaikh38@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] scsi: target: Replace strlcpy with strscpy | expand |
On Wed, Aug 30, 2023 at 09:53:30PM +0000, Justin Stitt wrote: > On Wed, Aug 30, 2023 at 09:07:24PM +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> > > --- > > v2: > > * Replace all instances of strlcpy in this file instead of just 1. > > > > v1: > > * https://lore.kernel.org/all/20230830200717.4129442-1-azeemshaikh38@gmail.com/ > > > > drivers/target/target_core_configfs.c | 27 ++++++++++++--------------- > > 1 file changed, 12 insertions(+), 15 deletions(-) > > > > diff --git a/drivers/target/target_core_configfs.c b/drivers/target/target_core_configfs.c > > index 936e5ff1b209..10a22a428267 100644 > > --- a/drivers/target/target_core_configfs.c > > +++ b/drivers/target/target_core_configfs.c > > @@ -1392,16 +1392,15 @@ 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 || strlen(stripped) > INQUIRY_VENDOR_LEN) { > > pr_err("Emulated T10 Vendor Identification exceeds" > > " INQUIRY_VENDOR_LEN: " __stringify(INQUIRY_VENDOR_LEN) > > "\n"); > > Should we be explicitly checking for `len == -E2BIG` instead of the more > generic `len < 0`? Perhaps this is a nitpick but I prefer the former. For robustness, we want to just do the "< 0" test -- that way if strscpy() gains a new errno (for some unimaginable reason) then all the code testing for "< 0" will continue to work sanely. -Kees
diff --git a/drivers/target/target_core_configfs.c b/drivers/target/target_core_configfs.c index 936e5ff1b209..10a22a428267 100644 --- a/drivers/target/target_core_configfs.c +++ b/drivers/target/target_core_configfs.c @@ -1392,16 +1392,15 @@ 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 || strlen(stripped) > INQUIRY_VENDOR_LEN) { pr_err("Emulated T10 Vendor Identification exceeds" " INQUIRY_VENDOR_LEN: " __stringify(INQUIRY_VENDOR_LEN) "\n"); @@ -1448,16 +1447,15 @@ 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 || strlen(stripped) > INQUIRY_MODEL_LEN) { pr_err("Emulated T10 Vendor exceeds INQUIRY_MODEL_LEN: " __stringify(INQUIRY_MODEL_LEN) "\n"); @@ -1504,16 +1502,15 @@ 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 || strlen(stripped) > 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> --- v2: * Replace all instances of strlcpy in this file instead of just 1. v1: * https://lore.kernel.org/all/20230830200717.4129442-1-azeemshaikh38@gmail.com/ drivers/target/target_core_configfs.c | 27 ++++++++++++--------------- 1 file changed, 12 insertions(+), 15 deletions(-) -- 2.42.0.283.g2d96d420d3-goog