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usb: gadget: f_mass_storage: fix null pointer dereference in fsg_common_set_num_buffers()

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Previously fsg_num_buffers_validate() was removed as it was not
necessary due to Kconfig setting the limits for n from 2 to 256 with
default as 2. However, setting the page content in such a way that
kstrtou8() reflects n value as either 0 or 1 bypasses these
restrictions leading to a null pointer dereference if n is 0. Fix
this by adding a check for n < 2 and returning -EINVAL if n is
either 0 or 1 consistent with Kconfig logic.

Reported-by: syzbot+791be35f1fbcc85d06d7@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=791be35f1fbcc85d06d7
Fixes: fe5a6c48fd ("usb: gadget: storage: get rid of fsg_num_buffers_validate()")
Cc: stable <stable@kernel.org>
Signed-off-by: Jeffin Philip <jeffinphilip14@gmail.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Link: https://patch.msgid.link/20260818035904.10324-1-jeffinphilip14@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jeffin Philip 2026-08-18 09:29:04 +05:30 committed by Greg Kroah-Hartman
parent 9f6f095bee
commit 2c0f5ca486
1 changed files with 3 additions and 0 deletions
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3
drivers/usb/gadget/function/f_mass_storage.c
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@ -2747,6 +2747,9 @@ int fsg_common_set_num_buffers(struct fsg_common *common, unsigned int n)
struct fsg_buffhd *bh, *buffhds;
int i;
if (n < 2)
return -EINVAL;
buffhds = kzalloc_objs(*buffhds, n);
if (!buffhds)
return -ENOMEM;