From: Tamura Dai kirinode0@gmail.com
[ Upstream commit 6c038b58a2dc5a008c7e7a1297f5aaa4deaaaa7e ]
sof_pdata->tplg_filename can have address allocated by kstrdup() and can be overwritten. Memory leak was detected with kmemleak:
unreferenced object 0xffff88812391ff60 (size 16): comm "kworker/4:1", pid 161, jiffies 4294802931 hex dump (first 16 bytes): 73 6f 66 2d 68 64 61 2d 67 65 6e 65 72 69 63 00 sof-hda-generic. backtrace (crc 4bf1675c): __kmalloc_node_track_caller_noprof+0x49c/0x6b0 kstrdup+0x46/0xc0 hda_machine_select.cold+0x1de/0x12cf [snd_sof_intel_hda_generic] sof_init_environment+0x16f/0xb50 [snd_sof] sof_probe_continue+0x45/0x7c0 [snd_sof] sof_probe_work+0x1e/0x40 [snd_sof] process_one_work+0x894/0x14b0 worker_thread+0x5e5/0xfb0 kthread+0x39d/0x760 ret_from_fork+0x31/0x70 ret_from_fork_asm+0x1a/0x30
Signed-off-by: Tamura Dai kirinode0@gmail.com Link: https://patch.msgid.link/20250615235548.8591-1-kirinode0@gmail.com Signed-off-by: Mark Brown broonie@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org ---
**YES**
This commit should be backported to stable kernel trees. Here's my extensive analysis:
## 1. **This fixes a real memory leak bug**
The kmemleak trace in the commit message shows concrete evidence of a memory leak: ``` unreferenced object 0xffff88812391ff60 (size 16): comm "kworker/4:1", pid 161, jiffies 4294802931 hex dump (first 16 bytes): 73 6f 66 2d 68 64 61 2d 67 65 6e 65 72 69 63 00 sof-hda-generic. ```
## 2. **The bug mechanism is clear**
Looking at the code changes, the leak occurs because: - `remove_file_ext()` allocates memory with `kstrdup()` - This allocated pointer is assigned to `sof_pdata->tplg_filename` - Later in `hda_machine_select()`, this pointer can be overwritten multiple times (lines 1373, 1413, 1452, 1473, 1484 all show `devm_kasprintf()` calls that reassign `sof_pdata->tplg_filename`) - Each overwrite leaks the previously allocated memory
## 3. **The fix is minimal and contained**
The change is extremely focused: ```diff -static char *remove_file_ext(const char *tplg_filename) +static char *remove_file_ext(struct device *dev, const char *tplg_filename) { char *filename, *tmp;
- filename = kstrdup(tplg_filename, GFP_KERNEL); + filename = devm_kstrdup(dev, tplg_filename, GFP_KERNEL); ```
Only two lines change: the function signature and the allocation call. The caller already has access to the device pointer, so the integration is trivial.
## 4. **Low risk of regression**
- `devm_kstrdup()` is a well-established kernel API - The same function (`hda_machine_select()`) already uses multiple `devm_*` allocations, showing this is the established pattern - Device-managed memory is automatically freed on device removal, eliminating the leak
## 5. **This differs from the similar commits shown**
The historical commits provided were all marked "NO" for backporting, but they were: - Code cleanups (removing macros, using newer APIs) - Refactoring (renaming files) - Defensive programming (NULL checks)
This commit is fundamentally different - it fixes an actual bug that affects users.
## 6. **User impact is real**
- Systems with SOF audio that reload drivers (suspend/resume cycles, module reload) will leak memory - Long-running systems could accumulate significant memory waste - The leak happens in the probe path, a common operation
## 7. **The bug was recently introduced**
According to the kernel repository analysis, this bug was introduced in August 2024, making it relatively recent and likely present in current stable kernels that need the fix.
## Conclusion
This commit meets all the criteria for stable backporting: - Fixes a real bug (not a theoretical issue) - Minimal, contained change - Clear root cause and solution - Low regression risk - Follows established patterns in the codebase - Has actual user impact
The absence of a "Cc: stable" tag in the original commit appears to be an oversight rather than an intentional decision to exclude it from stable trees.
sound/soc/sof/intel/hda.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/sound/soc/sof/intel/hda.c b/sound/soc/sof/intel/hda.c index 9c8f79e55ec5d..624598c9e2df8 100644 --- a/sound/soc/sof/intel/hda.c +++ b/sound/soc/sof/intel/hda.c @@ -1209,11 +1209,11 @@ static int check_tplg_quirk_mask(struct snd_soc_acpi_mach *mach) return 0; }
-static char *remove_file_ext(const char *tplg_filename) +static char *remove_file_ext(struct device *dev, const char *tplg_filename) { char *filename, *tmp;
- filename = kstrdup(tplg_filename, GFP_KERNEL); + filename = devm_kstrdup(dev, tplg_filename, GFP_KERNEL); if (!filename) return NULL;
@@ -1297,7 +1297,7 @@ struct snd_soc_acpi_mach *hda_machine_select(struct snd_sof_dev *sdev) */ if (!sof_pdata->tplg_filename) { /* remove file extension if it exists */ - tplg_filename = remove_file_ext(mach->sof_tplg_filename); + tplg_filename = remove_file_ext(sdev->dev, mach->sof_tplg_filename); if (!tplg_filename) return NULL;