Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
Pre-existing issues: - [High] Unchecked return value of fb_deferred_io_init() in ssd1307fb_probe() leads to a NULL pointer dereference in fb_deferred_io_mmap(). -- commit 20b4c9f03621ce152d836b82e0b4d3c3cda114ce Author: Lorenzo Stoakes (ARM) <[email protected]> fbdev: defio: assert FBINFO_VIRTFB, drop VM_IO, add VM_MIXEDMAP This commit updates defio drivers to assert the FBINFO_VIRTFB flag, drops the VM_IO flag, and sets VM_MIXEDMAP since kernel-allocated memory is mapped. It also ensures the ssd1307fb driver sets FBINFO_VIRTFB during its probe. > diff --git a/drivers/video/fbdev/core/fb_defio.c > b/drivers/video/fbdev/core/fb_defio.c > index fd00b86e1ae60..fb359ecc39661 100644 > --- a/drivers/video/fbdev/core/fb_defio.c > +++ b/drivers/video/fbdev/core/fb_defio.c > @@ -366,13 +366,13 @@ int fb_deferred_io_mmap(struct fb_info *info, struct > vm_area_struct *vma) > { > vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot); > > + if (WARN_ON_ONCE(!(info->flags & FBINFO_VIRTFB))) > + return -EINVAL; > if (!try_module_get(THIS_MODULE)) > return -EINVAL; > > vma->vm_ops = &fb_deferred_io_vm_ops; > - vm_flags_set(vma, VM_DONTEXPAND | VM_DONTDUMP); > - if (!(info->flags & FBINFO_VIRTFB)) > - vm_flags_set(vma, VM_IO); > + vm_flags_set(vma, VM_MIXEDMAP | VM_DONTEXPAND | VM_DONTDUMP); > vma->vm_private_data = info->fbdefio_state; > > fb_deferred_io_state_get(info->fbdefio_state); /* released in > vma->vm_ops->close() */ [Severity: High] This isn't a bug introduced by this patch, but could this lead to a NULL pointer dereference if fb_deferred_io_init() previously failed? If memory allocation fails during fb_deferred_io_init() in the driver probe, it returns an error code and leaves info->fbdefio_state as NULL. When a userspace program maps the framebuffer, fb_deferred_io_mmap() unconditionally passes the NULL info->fbdefio_state to fb_deferred_io_state_get(), which will subsequently dereference it via kref_get(). [ ... ] > diff --git a/drivers/video/fbdev/ssd1307fb.c b/drivers/video/fbdev/ssd1307fb.c > index c4fdecafd8560..958514a354338 100644 > --- a/drivers/video/fbdev/ssd1307fb.c > +++ b/drivers/video/fbdev/ssd1307fb.c > @@ -763,6 +763,8 @@ static int ssd1307fb_probe(struct i2c_client *client) > info->fix.smem_start = __pa(vmem); > info->fix.smem_len = vmem_size; > > + info->flags = FBINFO_VIRTFB; > + > fb_deferred_io_init(info); [Severity: High] This is a pre-existing issue, but the return value of fb_deferred_io_init() is ignored here in ssd1307fb_probe(). Should we check the return value of fb_deferred_io_init() and handle the potential allocation failure so we don't proceed with a NULL info->fbdefio_state? -- Sashiko AI review ยท https://sashiko.dev/#/patchset/20260908-b4-mmap-prepare-vma-flag-sanify-v1-0-dacf19cce...@kernel.org?part=18
