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| author | Ivy Lopez <skunkolee@gmail.com> | 2026-08-15 18:54:33 -0600 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2026-09-01 16:41:17 +0200 |
| commit | fed0aa7c6eaedc6c0d4e362fc91724aa47be4a7b (patch) | |
| tree | 6dea788e82bad85ef459cf55f58abb502c6e4103 | |
| parent | e24e3370356bddb65d667985a332b5f8aeeb5f97 (diff) | |
| download | linux-fed0aa7c6eaedc6c0d4e362fc91724aa47be4a7b.tar.gz linux-fed0aa7c6eaedc6c0d4e362fc91724aa47be4a7b.zip | |
usb: gadget: f_midi2: fix use-after-free in string attribute show path
f_midi2_opts_str_show() takes the string lock internally, but its
callers dereference the opts->info.<field> pointer before calling it,
outside the lock. This races with f_midi2_opts_str_store(), which
frees the old string under opts->lock when the attribute is written
concurrently, the show path can read a pointer that gets freed
before the lock inside str_show() is even taken.
Change f_midi2_opts_str_show() to take a pointer to the string field,
matching the existing pattern in f_midi2_opts_str_store(), and
dereference it only after the lock is held. Update all three callers
(iface_name, block name, and the EP string option macro) accordingly.
Reported-by: syzbot+2280f1cca5e6b0c353e4@syzkaller.appspotmail.com
Cc: stable <stable@kernel.org>
Closes: https://syzkaller.appspot.com/bug?extid=2280f1cca5e6b0c353e4
Signed-off-by: Ivy Lopez <skunkolee@gmail.com>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20260816005434.34018-1-skunkolee@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/usb/gadget/function/f_midi2.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/drivers/usb/gadget/function/f_midi2.c b/drivers/usb/gadget/function/f_midi2.c index e0b743dfaba5..5b8b18281989 100644 --- a/drivers/usb/gadget/function/f_midi2.c +++ b/drivers/usb/gadget/function/f_midi2.c @@ -2177,13 +2177,13 @@ end: /* generic show/store for string */ static ssize_t f_midi2_opts_str_show(struct f_midi2_opts *opts, - const char *str, char *page) + const char **strp, char *page) { int result = 0; mutex_lock(&opts->lock); - if (str) - result = scnprintf(page, PAGE_SIZE, "%s\n", str); + if (*strp) + result = scnprintf(page, PAGE_SIZE, "%s\n", *strp); mutex_unlock(&opts->lock); return result; } @@ -2277,7 +2277,7 @@ static ssize_t f_midi2_block_opts_name_show(struct config_item *item, { struct f_midi2_block_opts *opts = to_f_midi2_block_opts(item); - return f_midi2_opts_str_show(opts->ep->opts, opts->info.name, page); + return f_midi2_opts_str_show(opts->ep->opts, &opts->info.name, page); } static ssize_t f_midi2_block_opts_name_store(struct config_item *item, @@ -2434,7 +2434,7 @@ static ssize_t f_midi2_ep_opts_##name##_show(struct config_item *item, \ char *page) \ { \ struct f_midi2_ep_opts *opts = to_f_midi2_ep_opts(item); \ - return f_midi2_opts_str_show(opts->opts, opts->info.name, page);\ + return f_midi2_opts_str_show(opts->opts, &opts->info.name, page);\ } \ \ static ssize_t f_midi2_ep_opts_##name##_store(struct config_item *item, \ @@ -2589,7 +2589,7 @@ static ssize_t f_midi2_opts_iface_name_show(struct config_item *item, { struct f_midi2_opts *opts = to_f_midi2_opts(item); - return f_midi2_opts_str_show(opts, opts->info.iface_name, page); + return f_midi2_opts_str_show(opts, &opts->info.iface_name, page); } static ssize_t f_midi2_opts_iface_name_store(struct config_item *item, |