{"id":2231663,"url":"http://patchwork.ozlabs.org/api/patches/2231663/?format=json","web_url":"http://patchwork.ozlabs.org/project/linuxppc-dev/patch/8fda3212a1ad48879c174e92f67472d9b9f1c3b7.1777606826.git.ritesh.list@gmail.com/","project":{"id":2,"url":"http://patchwork.ozlabs.org/api/projects/2/?format=json","name":"Linux PPC development","link_name":"linuxppc-dev","list_id":"linuxppc-dev.lists.ozlabs.org","list_email":"linuxppc-dev@lists.ozlabs.org","web_url":"https://github.com/linuxppc/wiki/wiki","scm_url":"https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git","webscm_url":"https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/","list_archive_url":"https://lore.kernel.org/linuxppc-dev/","list_archive_url_format":"https://lore.kernel.org/linuxppc-dev/{}/","commit_url_format":"https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/commit/?id={}"},"msgid":"<8fda3212a1ad48879c174e92f67472d9b9f1c3b7.1777606826.git.ritesh.list@gmail.com>","list_archive_url":"https://lore.kernel.org/linuxppc-dev/8fda3212a1ad48879c174e92f67472d9b9f1c3b7.1777606826.git.ritesh.list@gmail.com/","date":"2026-05-01T04:11:44","name":"[v3,5/9] pseries/papr-hvpipe: Fix the usage of copy_to_user()","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"4c72be5772b08c33f82b9bb035c85b8214dc3c6b","submitter":{"id":79126,"url":"http://patchwork.ozlabs.org/api/people/79126/?format=json","name":"Ritesh Harjani (IBM)","email":"ritesh.list@gmail.com"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/linuxppc-dev/patch/8fda3212a1ad48879c174e92f67472d9b9f1c3b7.1777606826.git.ritesh.list@gmail.com/mbox/","series":[{"id":502420,"url":"http://patchwork.ozlabs.org/api/series/502420/?format=json","web_url":"http://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=502420","date":"2026-05-01T04:11:39","name":"pseries/papr-hvpipe: Fix deadlock, races and misc cleanups","version":3,"mbox":"http://patchwork.ozlabs.org/series/502420/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2231663/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2231663/checks/","tags":{},"related":[],"headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","linuxppc-dev@lists.ozlabs.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256\n header.s=20251104 header.b=SJpvlPnY;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=lists.ozlabs.org\n (client-ip=112.213.38.117; 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If there was\nan error writing bytes into the user buffer, i.e. if copy_to_user\nreturns a non-zero value, then we should simply return -EFAULT from the\n->read() call.\n\nOtherwise, in the non-patched version, we may end up mixing\n\"bytes_not_copied + bytes_copied (HVPIPE_HDR_LEN)\" as the return value\nto the user in ->read() call\n\nAlso let's make sure we clear the hvpipe_status flag, if we have\nconsumed the hvpipe msg by making the rtas call. ret = -EFAULT means\ncopy_to_user has failed but that still means that the msg was read from\nthe hvpipe, hence for both cases, success & -EFAULT, we should clear the\nHVPIPE_MSG_AVAILABLE flag in hvpipe_status.\n\nCc: stable@vger.kernel.org\nFixes: cebdb522fd3edd1 (\"powerpc/pseries: Receive payload with ibm,receive-hvpipe-msg RTAS\")\nSigned-off-by: Ritesh Harjani (IBM) \n---\n arch/powerpc/platforms/pseries/papr-hvpipe.c | 23 ++++++++++++--------\n 1 file changed, 14 insertions(+), 9 deletions(-)","diff":"diff --git a/arch/powerpc/platforms/pseries/papr-hvpipe.c b/arch/powerpc/platforms/pseries/papr-hvpipe.c\nindex 800649f309a5..c007560d2d8c 100644\n--- a/arch/powerpc/platforms/pseries/papr-hvpipe.c\n+++ b/arch/powerpc/platforms/pseries/papr-hvpipe.c\n@@ -206,10 +206,11 @@ static int hvpipe_rtas_recv_msg(char __user *buf, int size)\n \t\t\t\t\tbytes_written, size);\n \t\t\t\tbytes_written = size;\n \t\t\t}\n-\t\t\tret = copy_to_user(buf,\n+\t\t\tif (copy_to_user(buf,\n \t\t\t\t\trtas_work_area_raw_buf(work_area),\n-\t\t\t\t\tbytes_written);\n-\t\t\tif (!ret)\n+\t\t\t\t\tbytes_written))\n+\t\t\t\tret = -EFAULT;\n+\t\t\telse\n \t\t\t\tret = bytes_written;\n \t\t}\n \t} else {\n@@ -328,7 +329,7 @@ static ssize_t papr_hvpipe_handle_read(struct file *file,\n \n \tstruct hvpipe_source_info *src_info = file->private_data;\n \tstruct papr_hvpipe_hdr hdr = {};\n-\tlong ret;\n+\tssize_t ret = 0;\n \n \t/*\n \t * Return -ENXIO during migration\n@@ -376,7 +377,7 @@ static ssize_t papr_hvpipe_handle_read(struct file *file,\n \n \tret = copy_to_user(buf, &hdr, HVPIPE_HDR_LEN);\n \tif (ret)\n-\t\treturn ret;\n+\t\treturn -EFAULT;\n \n \t/*\n \t * Message event has payload, so get the payload with\n@@ -385,19 +386,23 @@ static ssize_t papr_hvpipe_handle_read(struct file *file,\n \tif (hdr.flags & HVPIPE_MSG_AVAILABLE) {\n \t\tret = hvpipe_rtas_recv_msg(buf + HVPIPE_HDR_LEN,\n \t\t\t\tsize - HVPIPE_HDR_LEN);\n-\t\tif (ret > 0) {\n+\t\t/*\n+\t\t * Always clear MSG_AVAILABLE once the RTAS call has drained\n+\t\t * the message, regardless of whether copy_to_user succeeded.\n+\t\t */\n+\t\tif (ret >= 0 || ret == -EFAULT)\n \t\t\tsrc_info->hvpipe_status &= ~HVPIPE_MSG_AVAILABLE;\n-\t\t\tret += HVPIPE_HDR_LEN;\n-\t\t}\n \t} else if (hdr.flags & HVPIPE_LOST_CONNECTION) {\n \t\t/*\n \t\t * Hypervisor is closing the pipe for the specific\n \t\t * source. So notify user space.\n \t\t */\n \t\tsrc_info->hvpipe_status &= ~HVPIPE_LOST_CONNECTION;\n-\t\tret = HVPIPE_HDR_LEN;\n \t}\n \n+\tif (ret >= 0)\n+\t\tret += HVPIPE_HDR_LEN;\n+\n \treturn ret;\n }\n \n","prefixes":["v3","5/9"]}