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bpf: Fix error return value in bpf_copy_from_user_dynptr

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On error, copy_from_user returns number of bytes not copied to
destination, but current implementation of copy_user_data_sleepable does
not handle that correctly and returns it as error value, which may
confuse user, expecting meaningful negative error value.

Fixes: a498ee7576 ("bpf: Implement dynptr copy kfuncs")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250523181705.261585-1-mykyta.yatsenko5@gmail.com
This commit is contained in:
Mykyta Yatsenko
2025-05-23 19:17:05 +01:00
committed by Andrii Nakryiko
parent bfccacdf93
commit 079e5c56a5
1 changed files with 6 additions and 2 deletions
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8
kernel/trace/bpf_trace.c
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@@ -3555,8 +3555,12 @@ static __always_inline int copy_user_data_sleepable(void *dst, const void *unsaf
{
int ret;
if (!tsk) /* Read from the current task */
return copy_from_user(dst, (const void __user *)unsafe_src, size);
if (!tsk) { /* Read from the current task */
ret = copy_from_user(dst, (const void __user *)unsafe_src, size);
if (ret)
return -EFAULT;
return 0;
}
ret = access_process_vm(tsk, (unsigned long)unsafe_src, dst, size, 0);
if (ret != size)