[PATCH 02/11] fbdev: Transfer video= option strings to caller; clarify ownership
From: Thomas Zimmermann <tzimmermann@suse.de>
Date: 2023-02-09 13:55:26
Also in:
dri-devel, linux-fbdev
Subsystem:
framebuffer core, framebuffer layer, the rest · Maintainers:
Simona Vetter, Helge Deller, Linus Torvalds
In fb_get_options(), always duplicate the returned option string and transfer ownership of the memory to the function's caller. Until now, only the global option string got duplicated and transferred to the caller; the per-driver options were owned by fb_get_options(). In the end, it was impossible for the function's caller to detect if it had to release the string's memory buffer. Hence, all calling drivers leak the memory buffer. The leaks have existed ever since, but drivers only call fb_get_option() once as part of module initialization. So the amount of leaked memory is not significant. Fix the semantics of fb_get_option() by unconditionally transferring ownership of the memory buffer to the caller. Later patches can resolve the memory leaks in the fbdev drivers. Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> --- drivers/video/fbdev/core/fb_cmdline.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-)
diff --git a/drivers/video/fbdev/core/fb_cmdline.c b/drivers/video/fbdev/core/fb_cmdline.c
index 6792010d6716..702b00b71870 100644
--- a/drivers/video/fbdev/core/fb_cmdline.c
+++ b/drivers/video/fbdev/core/fb_cmdline.c@@ -30,13 +30,17 @@ EXPORT_SYMBOL_GPL(fb_mode_option); * (video=<name>:<options>) * @option: the option will be stored here * + * The caller owns the string returned in @option and is + * responsible for releasing the memory. + * * NOTE: Needed to maintain backwards compatibility */ int fb_get_options(const char *name, char **option) { - char *opt, *options = NULL; + const char *options = NULL; int retval = 0; int name_len = strlen(name), i; + char *opt; if (name_len && ofonly && strncmp(name, "offb", 4)) retval = 1;
@@ -55,12 +59,16 @@ int fb_get_options(const char *name, char **option) } /* No match, pass global option */ if (!options && option && fb_mode_option) - options = kstrdup(fb_mode_option, GFP_KERNEL); + options = fb_mode_option; if (options && !strncmp(options, "off", 3)) retval = 1; - if (option) - *option = options; + if (option) { + if (options) + *option = kstrdup(options, GFP_KERNEL); + else + *option = NULL; + } return retval; }
--
2.39.1