* [PATCH V2] sysfs: Add sysfs_emit and sysfs_emit_at to format sysfs output @ 2020-08-29 23:48 Joe Perches 2020-08-30 0:43 ` Joe Perches 2020-09-06 17:24 ` Joe Perches 0 siblings, 2 replies; 8+ messages in thread From: Joe Perches @ 2020-08-29 23:48 UTC (permalink / raw) To: Greg Kroah-Hartman, Rafael J. Wysocki Cc: Kees Cook, Gustavo A . R . Silva, Denis Efremov, Julia Lawall, Alex Dewar, Jonathan Corbet, linux-doc, linux-kernel Output defects can exist in sysfs content using sprintf and snprintf. sprintf does not know the PAGE_SIZE maximum of the temporary buffer used for outputting sysfs content and it's possible to overrun the PAGE_SIZE buffer length. Add a generic sysfs_emit function that knows that the size of the temporary buffer and ensures that no overrun is done. Add a generic sysfs_emit_at function that can be used in multiple call situations that also ensures that no overrun is done. Signed-off-by: Joe Perches <joe@perches.com> --- V2: Simplify sysfs_emit and add sysfs_emit_at Include Documentation change Documentation/filesystems/sysfs.rst | 8 ++--- fs/sysfs/file.c | 49 +++++++++++++++++++++++++++++ include/linux/sysfs.h | 15 +++++++++ 3 files changed, 67 insertions(+), 5 deletions(-) diff --git a/Documentation/filesystems/sysfs.rst b/Documentation/filesystems/sysfs.rst index ab0f7795792b..d44249050f4a 100644 --- a/Documentation/filesystems/sysfs.rst +++ b/Documentation/filesystems/sysfs.rst @@ -242,12 +242,10 @@ Other notes: is 4096. - show() methods should return the number of bytes printed into the - buffer. This is the return value of scnprintf(). + buffer. -- show() must not use snprintf() when formatting the value to be - returned to user space. If you can guarantee that an overflow - will never happen you can use sprintf() otherwise you must use - scnprintf(). +- show() should only use sysfs_emit() or sysfs_emit_at() when formatting + the value to be returned to user space. - store() should return the number of bytes used from the buffer. If the entire buffer has been used, just return the count argument. diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c index eb6897ab78e7..e8c6d20bab8e 100644 --- a/fs/sysfs/file.c +++ b/fs/sysfs/file.c @@ -707,3 +707,52 @@ int sysfs_change_owner(struct kobject *kobj, kuid_t kuid, kgid_t kgid) return 0; } EXPORT_SYMBOL_GPL(sysfs_change_owner); + +/** + * sysfs_emit - scnprintf equivalent, aware of PAGE_SIZE buffer. + * @buf: start of PAGE_SIZE buffer. + * @fmt: format + * @...: optional arguments to @format + * + * + * Returns number of characters written to @buf. + */ +int sysfs_emit(char *buf, const char *fmt, ...) +{ + va_list args; + int len; + + va_start(args, fmt); + len = vscnprintf(buf, PAGE_SIZE, fmt, args); + va_end(args); + + return len; +} +EXPORT_SYMBOL_GPL(sysfs_emit); + +/** + * sysfs_emit_at - scnprintf equivalent, aware of PAGE_SIZE buffer. + * @buf: start of PAGE_SIZE buffer. + * @at: offset in @buf to start write in bytes + * @at must be >= 0 && < PAGE_SIZE + * @fmt: format + * @...: optional arguments to @fmt + * + * + * Returns number of characters written starting at &@buf[@at]. + */ +int sysfs_emit_at(char *buf, int at, const char *fmt, ...) +{ + va_list args; + int len; + + if (WARN(at < 0 || at >= PAGE_SIZE, "invalid sysfs_emit_at: %d\n", at)) + return 0; + + va_start(args, fmt); + len = vscnprintf(buf + at, PAGE_SIZE - at, fmt, args); + va_end(args); + + return len; +} +EXPORT_SYMBOL_GPL(sysfs_emit_at); diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h index 34e84122f635..2caa34c1ca1a 100644 --- a/include/linux/sysfs.h +++ b/include/linux/sysfs.h @@ -329,6 +329,10 @@ int sysfs_groups_change_owner(struct kobject *kobj, int sysfs_group_change_owner(struct kobject *kobj, const struct attribute_group *groups, kuid_t kuid, kgid_t kgid); +__printf(2, 3) +int sysfs_emit(char *buf, const char *fmt, ...); +__printf(3, 4) +int sysfs_emit_at(char *buf, int at, const char *fmt, ...); #else /* CONFIG_SYSFS */ @@ -576,6 +580,17 @@ static inline int sysfs_group_change_owner(struct kobject *kobj, return 0; } +__printf(2, 3) +static inline int sysfs_emit(char *buf, const char *fmt, ...) +{ + return 0; +} + +__printf(3, 4) +static inline int sysfs_emit_at(char *buf, int at, const char *fmt, ...) +{ + return 0; +} #endif /* CONFIG_SYSFS */ static inline int __must_check sysfs_create_file(struct kobject *kobj, -- 2.26.0 ^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH V2] sysfs: Add sysfs_emit and sysfs_emit_at to format sysfs output 2020-08-29 23:48 [PATCH V2] sysfs: Add sysfs_emit and sysfs_emit_at to format sysfs output Joe Perches @ 2020-08-30 0:43 ` Joe Perches 2020-08-30 8:59 ` Julia Lawall ` (2 more replies) 2020-09-06 17:24 ` Joe Perches 1 sibling, 3 replies; 8+ messages in thread From: Joe Perches @ 2020-08-30 0:43 UTC (permalink / raw) To: Greg Kroah-Hartman, Rafael J. Wysocki Cc: Kees Cook, Gustavo A . R . Silva, Denis Efremov, Julia Lawall, Alex Dewar, Jonathan Corbet, linux-doc, linux-kernel On Sat, 2020-08-29 at 16:48 -0700, Joe Perches wrote: > Output defects can exist in sysfs content using sprintf and snprintf. > > sprintf does not know the PAGE_SIZE maximum of the temporary buffer > used for outputting sysfs content and it's possible to overrun the > PAGE_SIZE buffer length. > > Add a generic sysfs_emit function that knows that the size of the > temporary buffer and ensures that no overrun is done. > > Add a generic sysfs_emit_at function that can be used in multiple > call situations that also ensures that no overrun is done. This preliminary coccinelle script converts ~5000 instances treewide. There are still many remaining instances that could be converted. $ git grep -w sysfs_emit -- '*.[ch]'|wc -l 4702 $ git grep -w sysfs_emit_at -- '*.[ch]'|wc -l 229 $ cat sysfs_emit.cocci @@ identifier d_show =~ "^.*show.*$"; identifier arg1, arg2, arg3; @@ ssize_t d_show(struct device * - arg1 + dev , struct device_attribute * - arg2 + attr , char * - arg3 + buf ) { ... ( - arg1 + dev | - arg2 + attr | - arg3 + buf ) ... } @@ identifier d_show =~ "^.*show.*$"; identifier dev, attr, buf; @@ ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf) { <... return - sprintf(buf, + sysfs_emit(buf, ...); ...> } @@ identifier d_show =~ "^.*show.*$"; identifier dev, attr, buf; @@ ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf) { <... return - snprintf(buf, PAGE_SIZE, + sysfs_emit(buf, ...); ...> } @@ identifier d_show =~ "^.*show.*$"; identifier dev, attr, buf; @@ ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf) { <... return - scnprintf(buf, PAGE_SIZE, + sysfs_emit(buf, ...); ...> } @@ identifier d_show =~ "^.*show.*$"; identifier dev, attr, buf; expression chr; @@ ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf) { <... return - strcpy(buf, chr); + sysfs_emit(buf, chr); ...> } @@ identifier d_show =~ "^.*show.*$"; identifier dev, attr, buf; identifier len; @@ ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf) { <... len = - sprintf(buf, + sysfs_emit(buf, ...); ...> return len; } @@ identifier d_show =~ "^.*show.*$"; identifier dev, attr, buf; identifier len; @@ ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf) { <... len = - snprintf(buf, PAGE_SIZE, + sysfs_emit(buf, ...); ...> return len; } @@ identifier d_show =~ "^.*show.*$"; identifier dev, attr, buf; identifier len; @@ ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf) { <... len = - scnprintf(buf, PAGE_SIZE, + sysfs_emit(buf, ...); ...> return len; } @@ identifier d_show =~ "^.*show.*$"; identifier dev, attr, buf; identifier len; @@ ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf) { <... - len += scnprintf(buf + len, PAGE_SIZE - len, + len += sysfs_emit_at(buf, len, ...); ...> return len; } @@ identifier d_show =~ "^.*show.*$"; identifier dev, attr, buf; expression chr; @@ ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf) { - strcpy(buf, chr); - return strlen(buf); + return sysfs_emit(buf, chr); } @@ identifier k_show =~ "^.*show.*$"; identifier arg1, arg2, arg3; @@ ssize_t k_show(struct kobject * - arg1 + kobj , struct kobj_attribute * - arg2 + attr , char * - arg3 + buf ) { ... ( - arg1 + kobj | - arg2 + attr | - arg3 + buf ) ... } @@ identifier k_show =~ "^.*show.*$"; identifier kobj, attr, buf; @@ ssize_t k_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { <... return - sprintf(buf, + sysfs_emit(buf, ...); ...> } @@ identifier k_show =~ "^.*show.*$"; identifier kobj, attr, buf; @@ ssize_t k_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { <... return - snprintf(buf, PAGE_SIZE, + sysfs_emit(buf, ...); ...> } @@ identifier k_show =~ "^.*show.*$"; identifier kobj, attr, buf; @@ ssize_t k_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { <... return - scnprintf(buf, PAGE_SIZE, + sysfs_emit(buf, ...); ...> } @@ identifier k_show =~ "^.*show.*$"; identifier kobj, attr, buf; expression chr; @@ ssize_t k_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { <... return - strcpy(buf, chr); + sysfs_emit(buf, chr); ...> } @@ identifier k_show =~ "^.*show.*$"; identifier kobj, attr, buf; identifier len; @@ ssize_t k_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { <... len = - sprintf(buf, + sysfs_emit(buf, ...); ...> return len; } @@ identifier k_show =~ "^.*show.*$"; identifier kobj, attr, buf; identifier len; @@ ssize_t k_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { <... len = - snprintf(buf, PAGE_SIZE, + sysfs_emit(buf, ...); ...> return len; } @@ identifier k_show =~ "^.*show.*$"; identifier kobj, attr, buf; identifier len; @@ ssize_t k_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { <... len = - scnprintf(buf, PAGE_SIZE, + sysfs_emit(buf, ...); ...> return len; } @@ identifier k_show =~ "^.*show.*$"; identifier kobj, attr, buf; identifier len; @@ ssize_t k_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { <... - len += scnprintf(buf + len, PAGE_SIZE - len, + len += sysfs_emit_at(buf, len, ...); ...> return len; } @@ identifier k_show =~ "^.*show.*$"; identifier kobj, attr, buf; expression chr; @@ ssize_t k_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { - strcpy(buf, chr); - return strlen(buf); + return sysfs_emit(buf, chr); } ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH V2] sysfs: Add sysfs_emit and sysfs_emit_at to format sysfs output 2020-08-30 0:43 ` Joe Perches @ 2020-08-30 8:59 ` Julia Lawall 2020-08-30 15:25 ` Denis Efremov 2020-09-07 13:36 ` Greg Kroah-Hartman 2 siblings, 0 replies; 8+ messages in thread From: Julia Lawall @ 2020-08-30 8:59 UTC (permalink / raw) To: Joe Perches Cc: Greg Kroah-Hartman, Rafael J. Wysocki, Kees Cook, Gustavo A . R . Silva, Denis Efremov, Julia Lawall, Alex Dewar, Jonathan Corbet, linux-doc, linux-kernel On Sat, 29 Aug 2020, Joe Perches wrote: > On Sat, 2020-08-29 at 16:48 -0700, Joe Perches wrote: > > Output defects can exist in sysfs content using sprintf and snprintf. > > > > sprintf does not know the PAGE_SIZE maximum of the temporary buffer > > used for outputting sysfs content and it's possible to overrun the > > PAGE_SIZE buffer length. > > > > Add a generic sysfs_emit function that knows that the size of the > > temporary buffer and ensures that no overrun is done. > > > > Add a generic sysfs_emit_at function that can be used in multiple > > call situations that also ensures that no overrun is done. > > This preliminary coccinelle script converts ~5000 instances treewide. > There are still many remaining instances that could be converted. Except for the issue with the ...s that has been discussed, this looks basically reasonable to me. julia > > $ git grep -w sysfs_emit -- '*.[ch]'|wc -l > 4702 > $ git grep -w sysfs_emit_at -- '*.[ch]'|wc -l > 229 > > $ cat sysfs_emit.cocci > @@ > identifier d_show =~ "^.*show.*$"; > identifier arg1, arg2, arg3; > @@ > ssize_t d_show(struct device * > - arg1 > + dev > , struct device_attribute * > - arg2 > + attr > , char * > - arg3 > + buf > ) > { > ... > ( > - arg1 > + dev > | > - arg2 > + attr > | > - arg3 > + buf > ) > ... > } > > @@ > identifier d_show =~ "^.*show.*$"; > identifier dev, attr, buf; > @@ > > ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf) > { > <... > return > - sprintf(buf, > + sysfs_emit(buf, > ...); > ...> > } > > @@ > identifier d_show =~ "^.*show.*$"; > identifier dev, attr, buf; > @@ > > ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf) > { > <... > return > - snprintf(buf, PAGE_SIZE, > + sysfs_emit(buf, > ...); > ...> > } > > @@ > identifier d_show =~ "^.*show.*$"; > identifier dev, attr, buf; > @@ > > ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf) > { > <... > return > - scnprintf(buf, PAGE_SIZE, > + sysfs_emit(buf, > ...); > ...> > } > > @@ > identifier d_show =~ "^.*show.*$"; > identifier dev, attr, buf; > expression chr; > @@ > > ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf) > { > <... > return > - strcpy(buf, chr); > + sysfs_emit(buf, chr); > ...> > } > > @@ > identifier d_show =~ "^.*show.*$"; > identifier dev, attr, buf; > identifier len; > @@ > > ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf) > { > <... > len = > - sprintf(buf, > + sysfs_emit(buf, > ...); > ...> > return len; > } > > @@ > identifier d_show =~ "^.*show.*$"; > identifier dev, attr, buf; > identifier len; > @@ > > ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf) > { > <... > len = > - snprintf(buf, PAGE_SIZE, > + sysfs_emit(buf, > ...); > ...> > return len; > } > > @@ > identifier d_show =~ "^.*show.*$"; > identifier dev, attr, buf; > identifier len; > @@ > > ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf) > { > <... > len = > - scnprintf(buf, PAGE_SIZE, > + sysfs_emit(buf, > ...); > ...> > return len; > } > > @@ > identifier d_show =~ "^.*show.*$"; > identifier dev, attr, buf; > identifier len; > @@ > > ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf) > { > <... > - len += scnprintf(buf + len, PAGE_SIZE - len, > + len += sysfs_emit_at(buf, len, > ...); > ...> > return len; > } > > @@ > identifier d_show =~ "^.*show.*$"; > identifier dev, attr, buf; > expression chr; > @@ > > ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf) > { > - strcpy(buf, chr); > - return strlen(buf); > + return sysfs_emit(buf, chr); > } > > @@ > identifier k_show =~ "^.*show.*$"; > identifier arg1, arg2, arg3; > @@ > ssize_t k_show(struct kobject * > - arg1 > + kobj > , struct kobj_attribute * > - arg2 > + attr > , char * > - arg3 > + buf > ) > { > ... > ( > - arg1 > + kobj > | > - arg2 > + attr > | > - arg3 > + buf > ) > ... > } > > @@ > identifier k_show =~ "^.*show.*$"; > identifier kobj, attr, buf; > @@ > > ssize_t k_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) > { > <... > return > - sprintf(buf, > + sysfs_emit(buf, > ...); > ...> > } > > @@ > identifier k_show =~ "^.*show.*$"; > identifier kobj, attr, buf; > @@ > > ssize_t k_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) > { > <... > return > - snprintf(buf, PAGE_SIZE, > + sysfs_emit(buf, > ...); > ...> > } > > @@ > identifier k_show =~ "^.*show.*$"; > identifier kobj, attr, buf; > @@ > > ssize_t k_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) > { > <... > return > - scnprintf(buf, PAGE_SIZE, > + sysfs_emit(buf, > ...); > ...> > } > > @@ > identifier k_show =~ "^.*show.*$"; > identifier kobj, attr, buf; > expression chr; > @@ > > ssize_t k_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) > { > <... > return > - strcpy(buf, chr); > + sysfs_emit(buf, chr); > ...> > } > > @@ > identifier k_show =~ "^.*show.*$"; > identifier kobj, attr, buf; > identifier len; > @@ > > ssize_t k_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) > { > <... > len = > - sprintf(buf, > + sysfs_emit(buf, > ...); > ...> > return len; > } > > @@ > identifier k_show =~ "^.*show.*$"; > identifier kobj, attr, buf; > identifier len; > @@ > > ssize_t k_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) > { > <... > len = > - snprintf(buf, PAGE_SIZE, > + sysfs_emit(buf, > ...); > ...> > return len; > } > > @@ > identifier k_show =~ "^.*show.*$"; > identifier kobj, attr, buf; > identifier len; > @@ > > ssize_t k_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) > { > <... > len = > - scnprintf(buf, PAGE_SIZE, > + sysfs_emit(buf, > ...); > ...> > return len; > } > > @@ > identifier k_show =~ "^.*show.*$"; > identifier kobj, attr, buf; > identifier len; > @@ > > ssize_t k_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) > { > <... > - len += scnprintf(buf + len, PAGE_SIZE - len, > + len += sysfs_emit_at(buf, len, > ...); > ...> > return len; > } > > @@ > identifier k_show =~ "^.*show.*$"; > identifier kobj, attr, buf; > expression chr; > @@ > > ssize_t k_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) > { > - strcpy(buf, chr); > - return strlen(buf); > + return sysfs_emit(buf, chr); > } > > > ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH V2] sysfs: Add sysfs_emit and sysfs_emit_at to format sysfs output 2020-08-30 0:43 ` Joe Perches 2020-08-30 8:59 ` Julia Lawall @ 2020-08-30 15:25 ` Denis Efremov 2020-08-30 16:05 ` Joe Perches 2020-09-07 13:36 ` Greg Kroah-Hartman 2 siblings, 1 reply; 8+ messages in thread From: Denis Efremov @ 2020-08-30 15:25 UTC (permalink / raw) To: Joe Perches, Greg Kroah-Hartman, Rafael J. Wysocki Cc: Kees Cook, Gustavo A . R . Silva, Julia Lawall, Alex Dewar, Jonathan Corbet, linux-doc, linux-kernel On 8/30/20 3:43 AM, Joe Perches wrote: > $ cat sysfs_emit.cocci > @@ > identifier d_show =~ "^.*show.*$"; I think this additional pattern will allow to take more functions into the scope. @da@ identifier show, store; expression name, mode; @@ ( DEVICE_ATTR(name, mode, show, store) | DEVICE_ATTR_PREALLOC(name, mode, show, store) | DEVICE_ATTR_IGNORE_LOCKDEP(name, mode, show, store) ) @@ // I think device_show_ulong, device_show_int, device_show_bool // functions deserve explicit handling because they are somewhat // reference implementations. identifier d_show = { da.show, device_show_ulong, device_show_int, device_show_bool }; identifier dev, attr, buf; @@ * ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf) { ... } I tried also to handle DEVICE_ATTR_RW, but I failed to use fresh identifier. This doesn't work: @darw@ identifier name; @@ ( DEVICE_ATTR_RW(name) | DEVICE_ATTR_RO(name) | DEVICE_ATTR_WO(name) ) @@ identifier darw.name; fresh identifier d_show = name ## "_show"; // <== parse error identifier dev, attr, buf; @@ * ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf) { ... } Regards, Denis ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH V2] sysfs: Add sysfs_emit and sysfs_emit_at to format sysfs output 2020-08-30 15:25 ` Denis Efremov @ 2020-08-30 16:05 ` Joe Perches 0 siblings, 0 replies; 8+ messages in thread From: Joe Perches @ 2020-08-30 16:05 UTC (permalink / raw) To: Denis Efremov, Greg Kroah-Hartman, Rafael J. Wysocki Cc: Kees Cook, Gustavo A . R . Silva, Julia Lawall, Alex Dewar, Jonathan Corbet, linux-doc, linux-kernel On Sun, 2020-08-30 at 18:25 +0300, Denis Efremov wrote: > > On 8/30/20 3:43 AM, Joe Perches wrote: > > $ cat sysfs_emit.cocci > > @@ > > identifier d_show =~ "^.*show.*$"; > > I think this additional pattern will allow to take more functions into the scope. > > @da@ > identifier show, store; > expression name, mode; > @@ > > ( > DEVICE_ATTR(name, mode, show, store) > DEVICE_ATTR_PREALLOC(name, mode, show, store) > DEVICE_ATTR_IGNORE_LOCKDEP(name, mode, show, store) > ) Thanks Denis. I'll try that out too. A trivial grep shows there are at least 130+ DEVICE_ATTR functions that have a show function that doesn't include "show" in the function name. $ grep-2.5.4 -rP --include=*.[ch] '\bDEVICE_ATTR\s*\(\s*\w+\s*,\s*[^,]+,\s*[^,]*,[^;]+;' * | \ perl -p -e 's/[[:space:]]*//g; s/;/;\n/g' | \ cut -f3 -d, | \ grep -v show | \ sort | uniq | wc -l 139 > @@ > // I think device_show_ulong, device_show_int, device_show_bool > // functions deserve explicit handling because they are somewhat > // reference implementations. Those reference implementations could be send as a separate patch but this preliminary script does already handle them. I do like the idea below of renaming the show functions without _show in the name adding _show. > identifier d_show = { da.show, device_show_ulong, device_show_int, device_show_bool }; > identifier dev, attr, buf; > @@ > > * ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf) > { > ... > } > > > I tried also to handle DEVICE_ATTR_RW, but I failed to use fresh identifier. > This doesn't work: > > @darw@ > identifier name; > @@ > > ( > DEVICE_ATTR_RW(name) > DEVICE_ATTR_RO(name) > DEVICE_ATTR_WO(name) > ) > > @@ > identifier darw.name; > fresh identifier d_show = name ## "_show"; // <== parse error > identifier dev, attr, buf; > @@ > > * ssize_t d_show(struct device *dev, struct device_attribute *attr, char *buf) > { > ... > } > > > Regards, > Denis ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH V2] sysfs: Add sysfs_emit and sysfs_emit_at to format sysfs output 2020-08-30 0:43 ` Joe Perches 2020-08-30 8:59 ` Julia Lawall 2020-08-30 15:25 ` Denis Efremov @ 2020-09-07 13:36 ` Greg Kroah-Hartman 2 siblings, 0 replies; 8+ messages in thread From: Greg Kroah-Hartman @ 2020-09-07 13:36 UTC (permalink / raw) To: Joe Perches Cc: Rafael J. Wysocki, Kees Cook, Gustavo A . R . Silva, Denis Efremov, Julia Lawall, Alex Dewar, Jonathan Corbet, linux-doc, linux-kernel On Sat, Aug 29, 2020 at 05:43:58PM -0700, Joe Perches wrote: > On Sat, 2020-08-29 at 16:48 -0700, Joe Perches wrote: > > Output defects can exist in sysfs content using sprintf and snprintf. > > > > sprintf does not know the PAGE_SIZE maximum of the temporary buffer > > used for outputting sysfs content and it's possible to overrun the > > PAGE_SIZE buffer length. > > > > Add a generic sysfs_emit function that knows that the size of the > > temporary buffer and ensures that no overrun is done. > > > > Add a generic sysfs_emit_at function that can be used in multiple > > call situations that also ensures that no overrun is done. > > This preliminary coccinelle script converts ~5000 instances treewide. > There are still many remaining instances that could be converted. > > $ git grep -w sysfs_emit -- '*.[ch]'|wc -l > 4702 > $ git grep -w sysfs_emit_at -- '*.[ch]'|wc -l > 229 Can you send a patch that would at least convert the driver core code (drivers/base/*) to use these new helpers so we have an in-tree user when applying the first patch? thanks, greg k-h ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH V2] sysfs: Add sysfs_emit and sysfs_emit_at to format sysfs output 2020-08-29 23:48 [PATCH V2] sysfs: Add sysfs_emit and sysfs_emit_at to format sysfs output Joe Perches 2020-08-30 0:43 ` Joe Perches @ 2020-09-06 17:24 ` Joe Perches 2020-09-07 5:48 ` Greg Kroah-Hartman 1 sibling, 1 reply; 8+ messages in thread From: Joe Perches @ 2020-09-06 17:24 UTC (permalink / raw) To: Greg Kroah-Hartman, Rafael J. Wysocki Cc: Kees Cook, Gustavo A . R . Silva, Denis Efremov, Julia Lawall, Alex Dewar, Jonathan Corbet, linux-doc, linux-kernel On Sat, 2020-08-29 at 16:48 -0700, Joe Perches wrote: > Output defects can exist in sysfs content using sprintf and snprintf. > > sprintf does not know the PAGE_SIZE maximum of the temporary buffer > used for outputting sysfs content and it's possible to overrun the > PAGE_SIZE buffer length. > > Add a generic sysfs_emit function that knows that the size of the > temporary buffer and ensures that no overrun is done. > > Add a generic sysfs_emit_at function that can be used in multiple > call situations that also ensures that no overrun is done. > > Signed-off-by: Joe Perches <joe@perches.com> > --- > > V2: Simplify sysfs_emit and add sysfs_emit_at > Include Documentation change Greg? Rafael? Thoughts on this? One additional possibility is to validate the buf address to be page aligned by adding a test of buf and offset_in_page(buf) ie: WARN(!buf || offset_in_page(buf), etc... Output defects can exist in sysfs content using sprintf and snprintf. sprintf does not know the PAGE_SIZE maximum of the temporary buffer used for outputting sysfs content and it's possible to overrun the PAGE_SIZE buffer length. Add a generic sysfs_emit function that knows that the size of the temporary buffer and ensures that no overrun is done. Add a generic sysfs_emit_at function that can be used in multiple call situations that also ensures that no overrun is done. Validate the output buffer argument to be page aligned. Validate the offset len argument to be within the PAGE_SIZE buf. Signed-off-by: Joe Perches <joe@perches.com> --- fs/sysfs/file.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 55 insertions(+) diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c index eb6897ab78e7..96d0da65e088 100644 --- a/fs/sysfs/file.c +++ b/fs/sysfs/file.c @@ -15,6 +15,7 @@ #include <linux/list.h> #include <linux/mutex.h> #include <linux/seq_file.h> +#include <linux/mm.h> #include "sysfs.h" @@ -707,3 +708,57 @@ int sysfs_change_owner(struct kobject *kobj, kuid_t kuid, kgid_t kgid) return 0; } EXPORT_SYMBOL_GPL(sysfs_change_owner); + +/** + * sysfs_emit - scnprintf equivalent, aware of PAGE_SIZE buffer. + * @buf: start of PAGE_SIZE buffer. + * @fmt: format + * @...: optional arguments to @format + * + * + * Returns number of characters written to @buf. + */ +int sysfs_emit(char *buf, const char *fmt, ...) +{ + va_list args; + int len; + + if (WARN(!buf || offset_in_page(buf), + "invalid sysfs_emit: buf:%p\n", buf)) + return 0; + + va_start(args, fmt); + len = vscnprintf(buf, PAGE_SIZE, fmt, args); + va_end(args); + + return len; +} +EXPORT_SYMBOL_GPL(sysfs_emit); + +/** + * sysfs_emit_at - scnprintf equivalent, aware of PAGE_SIZE buffer. + * @buf: start of PAGE_SIZE buffer. + * @at: offset in @buf to start write in bytes + * @at must be >= 0 && < PAGE_SIZE + * @fmt: format + * @...: optional arguments to @fmt + * + * + * Returns number of characters written starting at &@buf[@at]. + */ +int sysfs_emit_at(char *buf, int at, const char *fmt, ...) +{ + va_list args; + int len; + + if (WARN(!buf || offset_in_page(buf) || at < 0 || at >= PAGE_SIZE, + "invalid sysfs_emit_at: buf:%p at:%d\n", buf, at)) + return 0; + + va_start(args, fmt); + len = vscnprintf(buf + at, PAGE_SIZE - at, fmt, args); + va_end(args); + + return len; +} +EXPORT_SYMBOL_GPL(sysfs_emit_at); ^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH V2] sysfs: Add sysfs_emit and sysfs_emit_at to format sysfs output 2020-09-06 17:24 ` Joe Perches @ 2020-09-07 5:48 ` Greg Kroah-Hartman 0 siblings, 0 replies; 8+ messages in thread From: Greg Kroah-Hartman @ 2020-09-07 5:48 UTC (permalink / raw) To: Joe Perches Cc: Rafael J. Wysocki, Kees Cook, Gustavo A . R . Silva, Denis Efremov, Julia Lawall, Alex Dewar, Jonathan Corbet, linux-doc, linux-kernel On Sun, Sep 06, 2020 at 10:24:20AM -0700, Joe Perches wrote: > On Sat, 2020-08-29 at 16:48 -0700, Joe Perches wrote: > > Output defects can exist in sysfs content using sprintf and snprintf. > > > > sprintf does not know the PAGE_SIZE maximum of the temporary buffer > > used for outputting sysfs content and it's possible to overrun the > > PAGE_SIZE buffer length. > > > > Add a generic sysfs_emit function that knows that the size of the > > temporary buffer and ensures that no overrun is done. > > > > Add a generic sysfs_emit_at function that can be used in multiple > > call situations that also ensures that no overrun is done. > > > > Signed-off-by: Joe Perches <joe@perches.com> > > --- > > > > V2: Simplify sysfs_emit and add sysfs_emit_at > > Include Documentation change > > Greg? Rafael? Thoughts on this? I like the idea, give me a chance to catch up on patches, it's still in my to-review queue... thanks, greg k-h ^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2020-09-07 13:53 UTC | newest] Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2020-08-29 23:48 [PATCH V2] sysfs: Add sysfs_emit and sysfs_emit_at to format sysfs output Joe Perches 2020-08-30 0:43 ` Joe Perches 2020-08-30 8:59 ` Julia Lawall 2020-08-30 15:25 ` Denis Efremov 2020-08-30 16:05 ` Joe Perches 2020-09-07 13:36 ` Greg Kroah-Hartman 2020-09-06 17:24 ` Joe Perches 2020-09-07 5:48 ` Greg Kroah-Hartman
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