[PATCH] fs/proc/kcore.c: Clear ret value in read_kcore_iter after successful iov_iter_zero

[PATCH] fs/proc/kcore.c: Clear ret value in read_kcore_iter after successful iov_iter_zero

[Jiri Olsa]

If iov_iter_zero succeeds after failed copy_from_kernel_nofault,
we need to reset the ret value to zero otherwise it will be returned
as final return value of read_kcore_iter.

This fixes objdump -d dump over /proc/kcore for me.

Cc: stable@vger.kernel.org
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Fixes: 3d5854d75e31 ("fs/proc/kcore.c: allow translation of physical memory addresses")
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 fs/proc/kcore.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
index 51446c59388f..c82c408e573e 100644
--- a/fs/proc/kcore.c
+++ b/fs/proc/kcore.c
@@ -600,6 +600,7 @@ static ssize_t read_kcore_iter(struct kiocb *iocb, struct iov_iter *iter)
 					ret = -EFAULT;
 					goto out;
 				}
+				ret = 0;
 			/*
 			 * We know the bounce buffer is safe to copy from, so
 			 * use _copy_to_iter() directly.
-- 
2.47.0

Re: [PATCH] fs/proc/kcore.c: Clear ret value in read_kcore_iter after successful iov_iter_zero

[Alexander Gordeev]

On Fri, Nov 22, 2024 at 12:11:18AM +0100, Jiri Olsa wrote:
> If iov_iter_zero succeeds after failed copy_from_kernel_nofault,
> we need to reset the ret value to zero otherwise it will be returned
> as final return value of read_kcore_iter.
> 
> This fixes objdump -d dump over /proc/kcore for me.
> 
> Cc: stable@vger.kernel.org
> Cc: Alexander Gordeev <agordeev@linux.ibm.com>
> Fixes: 3d5854d75e31 ("fs/proc/kcore.c: allow translation of physical memory addresses")
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
>  fs/proc/kcore.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
> index 51446c59388f..c82c408e573e 100644
> --- a/fs/proc/kcore.c
> +++ b/fs/proc/kcore.c
> @@ -600,6 +600,7 @@ static ssize_t read_kcore_iter(struct kiocb *iocb, struct iov_iter *iter)
>  					ret = -EFAULT;
>  					goto out;
>  				}
> +				ret = 0;
>  			/*
>  			 * We know the bounce buffer is safe to copy from, so
>  			 * use _copy_to_iter() directly.

Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>

Thank you, Jiri!

Re: [PATCH] fs/proc/kcore.c: Clear ret value in read_kcore_iter after successful iov_iter_zero

[Christian Brauner]

On Fri, 22 Nov 2024 00:11:18 +0100, Jiri Olsa wrote:
> If iov_iter_zero succeeds after failed copy_from_kernel_nofault,
> we need to reset the ret value to zero otherwise it will be returned
> as final return value of read_kcore_iter.
> 
> This fixes objdump -d dump over /proc/kcore for me.
> 
> 
> [...]

Applied to the vfs.fixes branch of the vfs/vfs.git tree.
Patches in the vfs.fixes branch should appear in linux-next soon.

Please report any outstanding bugs that were missed during review in a
new review to the original patch series allowing us to drop it.

It's encouraged to provide Acked-bys and Reviewed-bys even though the
patch has now been applied. If possible patch trailers will be updated.

Note that commit hashes shown below are subject to change due to rebase,
trailer updates or similar. If in doubt, please check the listed branch.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git
branch: vfs.fixes

[1/1] fs/proc/kcore.c: Clear ret value in read_kcore_iter after successful iov_iter_zero
      https://git.kernel.org/vfs/vfs/c/088f294609d8