From: Sebastian Ott Date: Fri, 6 Nov 2015 08:58:06 +0000 (+0100) Subject: s390/ipl: fix out of bounds access in scpdata_write X-Git-Tag: firefly_0821_release~176^2~672^2~8 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=e0bedada3a497d0640dd5db93e7ad0735f487492;p=firefly-linux-kernel-4.4.55.git s390/ipl: fix out of bounds access in scpdata_write The input buffer in reipl_fcp_scpdata_write is accessed out of bounds when an offset is specified. The problem is that the offset refers to the data we should write to and not to the buffer we read from. So instead of memcpy(scp_data, buf + off, count); we could just do memcpy(scp_data + off, buf, count); However we not only modify the data but also store its length. For this to work we'd need to remember a state per open FH. Since that's not possible with sysfs callbacks let's just fail when an offset is specified. Signed-off-by: Sebastian Ott Acked-by: Hendrik Brueckner Signed-off-by: Martin Schwidefsky --- diff --git a/arch/s390/kernel/ipl.c b/arch/s390/kernel/ipl.c index f6d8acd7e136..9f80f65c3d97 100644 --- a/arch/s390/kernel/ipl.c +++ b/arch/s390/kernel/ipl.c @@ -687,21 +687,14 @@ static ssize_t reipl_fcp_scpdata_write(struct file *filp, struct kobject *kobj, struct bin_attribute *attr, char *buf, loff_t off, size_t count) { + size_t scpdata_len = count; size_t padding; - size_t scpdata_len; - if (off < 0) - return -EINVAL; - - if (off >= DIAG308_SCPDATA_SIZE) - return -ENOSPC; - if (count > DIAG308_SCPDATA_SIZE - off) - count = DIAG308_SCPDATA_SIZE - off; - - memcpy(reipl_block_fcp->ipl_info.fcp.scp_data, buf + off, count); - scpdata_len = off + count; + if (off) + return -EINVAL; + memcpy(reipl_block_fcp->ipl_info.fcp.scp_data, buf, count); if (scpdata_len % 8) { padding = 8 - (scpdata_len % 8); memset(reipl_block_fcp->ipl_info.fcp.scp_data + scpdata_len, @@ -717,7 +710,7 @@ static ssize_t reipl_fcp_scpdata_write(struct file *filp, struct kobject *kobj, } static struct bin_attribute sys_reipl_fcp_scp_data_attr = __BIN_ATTR(scp_data, (S_IRUGO | S_IWUSR), reipl_fcp_scpdata_read, - reipl_fcp_scpdata_write, PAGE_SIZE); + reipl_fcp_scpdata_write, DIAG308_SCPDATA_SIZE); static struct bin_attribute *reipl_fcp_bin_attrs[] = { &sys_reipl_fcp_scp_data_attr,