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usb: mon_text: Replace snprintf() with the safer scnprintf() variant

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There is a general misunderstanding amongst engineers that {v}snprintf()
returns the length of the data *actually* encoded into the destination
array.  However, as per the C99 standard {v}snprintf() really returns
the length of the data that *would have been* written if there were
enough space for it.  This misunderstanding has led to buffer-overruns
in the past.  It's generally considered safer to use the {v}scnprintf()
variants in their place (or even sprintf() in simple cases).  So let's
do that.

Link: https://lwn.net/Articles/69419/
Link: https://github.com/KSPP/linux/issues/105
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20231213164246.1021885-11-lee@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Lee Jones 2023-12-13 16:42:39 +00:00 committed by Greg Kroah-Hartman
parent 7963256961
commit 9d4e3d15d7
1 changed files with 5 additions and 23 deletions
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28
drivers/usb/mon/mon_text.c
View file

@ -352,7 +352,7 @@ static int mon_text_open(struct inode *inode, struct file *file)
rp->r.rnf_error = mon_text_error; rp->r.rnf_error = mon_text_error;
rp->r.rnf_complete = mon_text_complete; rp->r.rnf_complete = mon_text_complete;
snprintf(rp->slab_name, SLAB_NAME_SZ, "mon_text_%p", rp); scnprintf(rp->slab_name, SLAB_NAME_SZ, "mon_text_%p", rp);
rp->e_slab = kmem_cache_create(rp->slab_name, rp->e_slab = kmem_cache_create(rp->slab_name,
sizeof(struct mon_event_text), sizeof(long), 0, sizeof(struct mon_event_text), sizeof(long), 0,
mon_text_ctor); mon_text_ctor);
@ -700,46 +700,28 @@ static const struct file_operations mon_fops_text_u = {
int mon_text_add(struct mon_bus *mbus, const struct usb_bus *ubus) int mon_text_add(struct mon_bus *mbus, const struct usb_bus *ubus)
{ {
enum { NAMESZ = 10 }; enum { NAMESZ = 12 };
char name[NAMESZ]; char name[NAMESZ];
int busnum = ubus? ubus->busnum: 0; int busnum = ubus? ubus->busnum: 0;
int rc;
if (mon_dir == NULL) if (mon_dir == NULL)
return 0; return 0;
if (ubus != NULL) { if (ubus != NULL) {
rc = snprintf(name, NAMESZ, "%dt", busnum); scnprintf(name, NAMESZ, "%dt", busnum);
if (rc <= 0 || rc >= NAMESZ)
goto err_print_t;
mbus->dent_t = debugfs_create_file(name, 0600, mon_dir, mbus, mbus->dent_t = debugfs_create_file(name, 0600, mon_dir, mbus,
&mon_fops_text_t); &mon_fops_text_t);
} }
rc = snprintf(name, NAMESZ, "%du", busnum); scnprintf(name, NAMESZ, "%du", busnum);
if (rc <= 0 || rc >= NAMESZ)
goto err_print_u;
mbus->dent_u = debugfs_create_file(name, 0600, mon_dir, mbus, mbus->dent_u = debugfs_create_file(name, 0600, mon_dir, mbus,
&mon_fops_text_u); &mon_fops_text_u);
rc = snprintf(name, NAMESZ, "%ds", busnum); scnprintf(name, NAMESZ, "%ds", busnum);
if (rc <= 0 || rc >= NAMESZ)
goto err_print_s;
mbus->dent_s = debugfs_create_file(name, 0600, mon_dir, mbus, mbus->dent_s = debugfs_create_file(name, 0600, mon_dir, mbus,
&mon_fops_stat); &mon_fops_stat);
return 1; return 1;
err_print_s:
debugfs_remove(mbus->dent_u);
mbus->dent_u = NULL;
err_print_u:
if (ubus != NULL) {
debugfs_remove(mbus->dent_t);
mbus->dent_t = NULL;
}
err_print_t:
return 0;
} }
void mon_text_del(struct mon_bus *mbus) void mon_text_del(struct mon_bus *mbus)