From: Tony Battersby <tonyb@xxxxxxxxxxxxxxx> commit 9426d3cef5000824e5f24f80ed5f42fb935f2488 upstream. (lightly modified commit message mostly by Linus Torvalds) The parsing code for /proc/scsi/scsi is disgusting and broken. We should have just used 'sscanf()' or something simple like that, but the logic may actually predate our kernel sscanf library routine for all I know. It certainly predates both git and BK histories. And we can't change it to be something sane like that now, because the string matching at the start is done case-insensitively, and the separator parsing between numbers isn't done at all, so *any* separator will work, including a possible terminating NUL character. This interface is root-only, and entirely for legacy use, so there is absolutely no point in trying to tighten up the parsing. Because any separator has traditionally worked, it's entirely possible that people have used random characters rather than the suggested space. So don't bother to try to pretty it up, and let's just make a minimal patch that can be back-ported and we can forget about this whole sorry thing for another two decades. Just make it at least not read past the end of the supplied data. Link: https://lore.kernel.org/linux-scsi/b570f5fe-cb7c-863a-6ed9-f6774c219b88@xxxxxxxxxxxxxxx/ Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Martin K Petersen <martin.petersen@xxxxxxxxxx> Cc: James Bottomley <jejb@xxxxxxxxxxxxx> Cc: Willy Tarreau <w@xxxxxx> Cc: stable@xxxxxxxxxx Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Tony Battersby <tonyb@xxxxxxxxxxxxxxx> Signed-off-by: Martin K Petersen <martin.petersen@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/scsi/scsi_proc.c | 30 +++++++++++++++++------------- 1 file changed, 17 insertions(+), 13 deletions(-) --- a/drivers/scsi/scsi_proc.c +++ b/drivers/scsi/scsi_proc.c @@ -406,7 +406,7 @@ static ssize_t proc_scsi_write(struct fi size_t length, loff_t *ppos) { int host, channel, id, lun; - char *buffer, *p; + char *buffer, *end, *p; int err; if (!buf || length > PAGE_SIZE) @@ -421,10 +421,14 @@ static ssize_t proc_scsi_write(struct fi goto out; err = -EINVAL; - if (length < PAGE_SIZE) - buffer[length] = '\0'; - else if (buffer[PAGE_SIZE-1]) - goto out; + if (length < PAGE_SIZE) { + end = buffer + length; + *end = '\0'; + } else { + end = buffer + PAGE_SIZE - 1; + if (*end) + goto out; + } /* * Usage: echo "scsi add-single-device 0 1 2 3" >/proc/scsi/scsi @@ -433,10 +437,10 @@ static ssize_t proc_scsi_write(struct fi if (!strncmp("scsi add-single-device", buffer, 22)) { p = buffer + 23; - host = simple_strtoul(p, &p, 0); - channel = simple_strtoul(p + 1, &p, 0); - id = simple_strtoul(p + 1, &p, 0); - lun = simple_strtoul(p + 1, &p, 0); + host = (p < end) ? simple_strtoul(p, &p, 0) : 0; + channel = (p + 1 < end) ? simple_strtoul(p + 1, &p, 0) : 0; + id = (p + 1 < end) ? simple_strtoul(p + 1, &p, 0) : 0; + lun = (p + 1 < end) ? simple_strtoul(p + 1, &p, 0) : 0; err = scsi_add_single_device(host, channel, id, lun); @@ -447,10 +451,10 @@ static ssize_t proc_scsi_write(struct fi } else if (!strncmp("scsi remove-single-device", buffer, 25)) { p = buffer + 26; - host = simple_strtoul(p, &p, 0); - channel = simple_strtoul(p + 1, &p, 0); - id = simple_strtoul(p + 1, &p, 0); - lun = simple_strtoul(p + 1, &p, 0); + host = (p < end) ? simple_strtoul(p, &p, 0) : 0; + channel = (p + 1 < end) ? simple_strtoul(p + 1, &p, 0) : 0; + id = (p + 1 < end) ? simple_strtoul(p + 1, &p, 0) : 0; + lun = (p + 1 < end) ? simple_strtoul(p + 1, &p, 0) : 0; err = scsi_remove_single_device(host, channel, id, lun); }
