Both add_slot_store() and remove_slot_store() try to fix up the drc_name copied from the store buffer by placing a NULL terminator at nbyte + 1 or in place of a '\n' if present. However, the static buffer that we copy the drc_name data into is not zeored and can contain anything past the n-th byte. This is problematic if a '\n' byte appears in that buffer after nbytes and the string copied into the store buffer was not NULL terminated to start with as the strchr() search for a '\n' byte will mark this incorrectly as the end of the drc_name string resulting in a drc_name string that contains garbage data after the n-th byte. The following debugging shows an example of the drmgr utility writing "PHB 4543" to the add_slot sysfs attribute, but add_slot_store logging a corrupted string value. [135823.702864] drmgr: drmgr: -c phb -a -s PHB 4543 -d 1 [135823.702879] add_slot_store: drc_name = PHB 4543°|<82>!, rc = -19 Fix this by NULL terminating the string when we copy it into our static buffer by coping nbytes + 1 of data from the store buffer. The code has already made sure that nbytes is not >= MAX_DRC_NAME_LEN and the store buffer is guaranteed to be zeroed beyond the nth-byte of data copied from the user. Further, since the string is now NULL terminated the code only needs to change '\n' to '\0' when present. Signed-off-by: Tyrel Datwyler <tyreld@xxxxxxxxxxxxx> --- drivers/pci/hotplug/rpadlpar_sysfs.c | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-) diff --git a/drivers/pci/hotplug/rpadlpar_sysfs.c b/drivers/pci/hotplug/rpadlpar_sysfs.c index cdbfa5df3a51..375087921284 100644 --- a/drivers/pci/hotplug/rpadlpar_sysfs.c +++ b/drivers/pci/hotplug/rpadlpar_sysfs.c @@ -34,12 +34,11 @@ static ssize_t add_slot_store(struct kobject *kobj, struct kobj_attribute *attr, if (nbytes >= MAX_DRC_NAME_LEN) return 0; - memcpy(drc_name, buf, nbytes); + memcpy(drc_name, buf, nbytes + 1); end = strchr(drc_name, '\n'); - if (!end) - end = &drc_name[nbytes]; - *end = '\0'; + if (end) + *end = '\0'; rc = dlpar_add_slot(drc_name); if (rc) @@ -65,12 +64,11 @@ static ssize_t remove_slot_store(struct kobject *kobj, if (nbytes >= MAX_DRC_NAME_LEN) return 0; - memcpy(drc_name, buf, nbytes); + memcpy(drc_name, buf, nbytes + 1); end = strchr(drc_name, '\n'); - if (!end) - end = &drc_name[nbytes]; - *end = '\0'; + if (end) + *end = '\0'; rc = dlpar_remove_slot(drc_name); if (rc) -- 2.27.0
