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author | Ingo Molnar <mingo@elte.hu> | 2008-11-18 14:23:08 (GMT) |
---|---|---|
committer | Ingo Molnar <mingo@elte.hu> | 2008-11-18 14:34:36 (GMT) |
commit | 10db4ef7b9a65b86e4d047671a1886f4c101a859 (patch) | |
tree | 2d47105e6cf1e88c5a83def331c5d6302578e607 /arch/x86/kernel/ds.c | |
parent | 93ce99e849433ede4ce8b410b749dc0cad1100b2 (diff) | |
download | linux-fsl-qoriq-10db4ef7b9a65b86e4d047671a1886f4c101a859.tar.xz |
x86, PEBS/DS: fix code flow in ds_request()
this compiler warning:
arch/x86/kernel/ds.c: In function 'ds_request':
arch/x86/kernel/ds.c:368: warning: 'context' may be used uninitialized in this function
Shows that the code flow in ds_request() is buggy - it goes into
the unlock+release-context path even when the context is not allocated
yet.
First allocate the context, then do the other checks.
Also, take care with GFP allocations under the ds_lock spinlock.
Cc: <stable@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/kernel/ds.c')
-rw-r--r-- | arch/x86/kernel/ds.c | 26 |
1 files changed, 21 insertions, 5 deletions
diff --git a/arch/x86/kernel/ds.c b/arch/x86/kernel/ds.c index ac1d5b0..d1a1214 100644 --- a/arch/x86/kernel/ds.c +++ b/arch/x86/kernel/ds.c @@ -236,17 +236,33 @@ static inline struct ds_context *ds_alloc_context(struct task_struct *task) struct ds_context *context = *p_context; if (!context) { + spin_unlock(&ds_lock); + context = kzalloc(sizeof(*context), GFP_KERNEL); - if (!context) + if (!context) { + spin_lock(&ds_lock); return NULL; + } context->ds = kzalloc(ds_cfg.sizeof_ds, GFP_KERNEL); if (!context->ds) { kfree(context); + spin_lock(&ds_lock); return NULL; } + spin_lock(&ds_lock); + /* + * Check for race - another CPU could have allocated + * it meanwhile: + */ + if (*p_context) { + kfree(context->ds); + kfree(context); + return *p_context; + } + *p_context = context; context->this = p_context; @@ -384,15 +400,15 @@ static int ds_request(struct task_struct *task, void *base, size_t size, spin_lock(&ds_lock); - error = -EPERM; - if (!check_tracer(task)) - goto out_unlock; - error = -ENOMEM; context = ds_alloc_context(task); if (!context) goto out_unlock; + error = -EPERM; + if (!check_tracer(task)) + goto out_unlock; + error = -EALREADY; if (context->owner[qual] == current) goto out_unlock; |